Heartbeat monitoring of virtual machines for initiating failover operations in a data storage management system, including operations by a master monitor node

ABSTRACT

An illustrative “VM heartbeat monitoring network” of heartbeat monitor nodes monitors target VMs in a data storage management system. Accordingly, target VMs are distributed and re-distributed among illustrative worker monitor nodes according to preferences in an illustrative VM distribution logic. Worker heartbeat monitor nodes use an illustrative ping monitoring logic to transmit special-purpose heartbeat packets to respective target VMs and to track ping responses. If a target VM is ultimately confirmed failed by its worker monitor node, an illustrative master monitor node triggers an enhanced storage manager to initiate failover for the failed VM. The enhanced storage manager communicates with the heartbeat monitor nodes and also manages VM failovers and other storage management operations in the system. Special features for cloud-to-cloud failover scenarios enable a VM in a first region of a public cloud to fail over to a second region.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

The present application is a continuation of, and claims priority to,U.S. patent application Ser. No. 15/716,391, filed Sep. 26, 2017 andtitled “HEARTBEAT MONITORING OF VIRTUAL MACHINES FOR INITIATING FAILOVEROPERATIONS IN A DATA STORAGE MANAGEMENT SYSTEM, INCLUDING OPERATIONS BYA MASTER MONITOR NODE,” which claims priority to U.S. Provisional PatentApplication Ser. No. 62/402,269, filed on Sep. 30, 2016 and titled“Heartbeat Monitoring of Virtual Machines for Initiating FailoverOperations in a Data Storage Management System;” and to U.S. ProvisionalPatent Application Ser. No. 62/604,988, filed on Jul. 28, 2017, andtitled “Heartbeat Monitoring of Virtual Machines for Initiating Failoverand/or Failback Operations in a Data Storage Management System,” each ofwhich is hereby incorporated by reference herein in its entirety. Anyand all applications for which a foreign or domestic priority claim isidentified in the Application Data Sheet of the present application arehereby incorporated by reference in their entireties herein under 37 CFR1.57.

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentand/or the patent disclosure as it appears in the United States Patentand Trademark Office patent file and/or records, but otherwise reservesall copyrights whatsoever.

BACKGROUND

Businesses recognize the commercial value of their data and seekreliable, cost-effective ways to protect the information stored on theircomputer networks while minimizing impact on productivity. A companymight back up critical computing systems such as databases, fileservers, web servers, virtual machines, and so on as part of a daily,weekly, or monthly maintenance schedule. The company may similarlyprotect computing systems used by its employees, such as those used byan accounting department, marketing department, engineering department,and so forth. Given the rapidly expanding volume of data undermanagement, companies also continue to seek innovative techniques formanaging data growth, for example by migrating data to lower-coststorage over time, reducing redundant data, pruning lower priority data,etc. Enterprises also increasingly view their stored data as a valuableasset and look for solutions that leverage their data. For instance,data analysis capabilities, information management, improved datapresentation and access features, and the like, are in increasingdemand.

The popularity of virtual machines (VMs) in today's data centers tendsto make them more important. VM failures need to be quickly discovered,so that standby or backup VM(s) can take over promptly.

SUMMARY

The present inventors devised systems and methods for monitoring virtualmachines (VMs) within the umbrella of a data storage management system.Certain VMs are specially targeted for ongoing heartbeat monitoring.Failed target VMs are called for failover to correspondingpre-configured replica VMs. The ongoing heartbeat monitoring isperformed by heartbeat monitor nodes executing in other VMs and/or onnonvirtualized computing devices—the so-called “worker monitor nodes”(“worker nodes” or “worker heartbeat monitor nodes”). The workerheartbeat monitor nodes are part of a larger “VM heartbeat monitoringnetwork” or “VM heartbeat monitoring system” that also comprises a“master monitor node” and one or more “observer monitor nodes” whichplay key roles in maintaining a robust architecture, which featuresbuilt-in coordination and redundancy. To increase robustness, observernodes are also configured in cloud-based computing resources.

Upon detecting a target-VM failure and confirming the failure with theVM's host server and/or VM data center controller to ensure that the VMis really in a failed state that requires failover, the illustrativeworker monitor node notifies the master monitor node, which in turncarries out its responsibility for notifying a storage manager of thisand any other failed VMs in the system. The storage manager not onlyinvokes and manages failover operations for the failed target VM(s)after receiving proper notice from the master monitor node, but alsomanages other storage management operations throughout the data storagemanagement system, such as backups, replication, archiving, contentindexing, restores, etc. Likewise, the storage manager manages failbackoperations from a site that was previously considered to be a failoverdestination back to the former source site, e.g., after the source datacenter recovers, after a failed over VM recovers, etc.

The illustrative VM heartbeat monitoring system comprises anillustrative ping monitoring logic that worker monitor nodes use fordetermining whether their target VMs are operational. To optimizeoperational efficiency, a master monitor node can be configured to alsooperate as a worker monitor node, thus performing a dual role. Tofurther optimize operational efficiency, the VMs targeted for heartbeatmonitoring are assigned (distributed) to available worker nodes based onan illustrative VM distribution logic that favors monitor nodes whichare “close to” the target VMs from a network topology perspective, e.g.,same-network, same-server, low hop count, low round-trip latency, etc.To further optimize operational efficiency, the illustrative mastermonitor node selection logic also favors “closeness” to the main locusof monitoring action, e.g., the source data center where most, if notall, target VMs operate. The master monitor executes the illustrative VMdistribution logic and informs worker monitor nodes of their respectivetarget VM lists. The master monitor node re-distributes target VMs whena worker monitor node fails.

The illustrative architecture supports a variety of source anddestination data centers. One illustrative configuration includes (i) asource data center, where the target VMs, master monitor node, andworker monitor node operate; (ii) a destination data center where VMsare replicated in case of a failover; (iii) one or more cloud-basedobserver monitor nodes that are meant to survive any catastrophicfailures at the source and to help the VM heartbeat monitoring networktransition to the failover destination; and (iv) a storage manager. Asecond illustrative configuration includes (i) a source data centerconfigured in a first region of a service provider's “public cloud”;(ii) a destination data center configured in a second region of theservice provider's “public cloud”; and (iii) a storage manager. Thesecond illustrative configuration comprises specialized cloud-to-cloudsupport logic that tunnels communications to and from the storagemanager through a firewalled master monitor node and also opens ports oncertain heartbeat monitor nodes for master node failover scenarios. Athird illustrative configuration optimizes operational efficiency byintegrating the storage manager into the firewalled master monitor nodeso that communications pathways are reduced and network topology issimplified. These illustrative configurations can be combined withoutlimitation according to the architecture described herein.

Some of the monitor nodes are specially configured to be members of aso-called quorum arrangement, e.g., master monitor node, worker monitornode(s), cloud-based observer node(s), and destination-based observernode(s). The quorum will survive failure of a minority of its members,thus enabling observer(s) at the destination to be promoted to workernode(s) and/or further enabling a new master node to emerge in case thepresent master monitor fails. Not every heartbeat monitor node in theillustrative systems need be a quorum member as the quorum should beconfigured with a view to long-term survivability rather thanload-balancing of target VM monitoring; accordingly worker monitor nodescan perform heartbeat monitoring of target VMs without participating inquorum operations.

On failover from source to destination, replica VMs are activated totake the place of the corresponding target VMs that failed at thesource. Accordingly, one or more observer monitors at the destinationare re-configured into worker monitor nodes for heartbeat monitoring ofthe newly activated target VMs at the destination, thus necessitatingthat VM distribution logic be executed anew. To do so, it may benecessary to elect a new master monitor node, if the existing master hasfailed.

The heartbeat monitor nodes communicate with each other by updatingcertain specially-configured data files that reside within a distributedfile system having an instance on each heartbeat monitor node. Theillustrative data files are specially configured to comprise informationneeded for managing heartbeat monitoring and for communicatinginformation among monitor nodes, e.g., each worker node's current listof target VMs, indications of failed target VMs, network and addressinginformation for the target VMs, etc. The updated data files arepromulgated to all heartbeat monitor nodes by the distributed filesystem. Thanks to so-called “watch” processes, changes received in theupdated data files are detected by each heartbeat monitor node, thusserving as a way of communicating information among heartbeat monitornodes. Specially configured watch processes detect whether quorum membernodes have failed, whether any worker monitor nodes have failed, as wellas detecting other important changes in the system.

The mutually coordinating infrastructure implemented among theillustrative heartbeat monitor nodes is based on but is not identical tothe ZooKeeper service devised by the Apache Software Foundation. Thus,each illustrative heartbeat monitor node comprises an Apache ZooKeeperservices, which is well known in the art and which enables highlyreliable distributed coordination among a plurality of nodes. Forexample, the illustrative heartbeat monitoring distributed file systemis coordinated and synchronized by underlying Apache ZooKeeperinfrastructure. Illustratively, monitor nodes that are designated to bequorum members run ZooKeeper server and client services; on the otherhand, monitor nodes that are designated to be workers but not quorummembers need only run ZooKeeper client services, though the invention isnot so limited. The data files' contents for node-to-node communicationsand the distributed file system organization are proprietary to theillustrative embodiments, while Apache ZooKeeper handles coordination ofthe distributed file system across monitor nodes. Thus, the illustrativearchitecture for VM heartbeat monitoring takes advantage of underlyingApache ZooKeeper utilities to coordinate and communicate informationacross heartbeat monitor nodes.

However, the illustrative architecture departs from the teachings ofApache ZooKeeper in regard to the organization and content of thedistributed file system, watch process configurations, ping monitoringlogic and associated ping packet design, VM distribution logic/rules,master node selection process, cloud-to-cloud support logic,node-to-node communications protocol using data files with specializedcontent for VM heartbeat monitoring, and administration/communicationfeatures to/from the storage manager and its management database. Theseheartbeat monitoring functional components as well as the underlyingApache ZooKeeper infrastructure are illustratively implemented in anenhanced data agent. The illustrative enhanced virtual server data agentalso comprises features for performing other VM storage managementoperations though the invention is not so limited. In alternativeembodiments, these functional components are separately deployed orcombined with other data agents and/or media agents without limitation.Although certain ZooKeeper features and services are used for some ofthe underlying infrastructure of the illustrative heartbeat monitoringnetwork, the invention is not so limited and numerous alternativeimplementations can be contemplated by someone having ordinary skill inthe art after reading the present disclosure. Furthermore, the presentinvention is not limited to relying on the ZooKeeper features describedherein, as will become clear to those having ordinary skill in the artafter reading the present disclosure.

Depending on the nature of the storage management operations that kepttrack of and protected the now-failed VM, e.g., replication, livesynchronization, etc., a suitable recovery operation is invoked by thestorage manager for restoring a VM to an operational state at thedestination data center to effectuate the failover. For failbackoperations, the reverse occurs, i.e., failback from destination tosource. Thus, the heartbeat monitor network detects VM failures throughVM heartbeat monitoring performed by monitor nodes and the storagemanager takes over and manages the recovery process by initiatingappropriate failover and/or failback operations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a block diagram illustrating an exemplary informationmanagement system.

FIG. 1B is a detailed view of a primary storage device, a secondarystorage device, and some examples of primary data and secondary copydata.

FIG. 1C is a block diagram of an exemplary information management systemincluding a storage manager, one or more data agents, and one or moremedia agents.

FIG. 1D is a block diagram illustrating a scalable informationmanagement system.

FIG. 1E illustrates certain secondary copy operations according to anexemplary storage policy.

FIGS. 1F-1H are block diagrams illustrating suitable data structuresthat may be employed by the information management system.

FIG. 2A illustrates a system and technique for synchronizing primarydata to a destination such as a failover site using secondary copy data.

FIG. 2B illustrates an information management system architectureincorporating use of a network file system (NFS) protocol forcommunicating between the primary and secondary storage subsystems.

FIG. 2C is a block diagram of an example of a highly scalable manageddata pool architecture.

FIG. 3 is a block diagram illustrating some salient portions of a system300 for heartbeat monitoring of virtual machines for initiating failoverand/or failback operations, according to an illustrative embodiment ofthe present invention.

FIG. 4 is a block diagram illustrating certain details of system 300,including a plurality of heartbeat monitor nodes in a quorumconfiguration.

FIG. 5 is a block diagram illustrating heartbeat monitor nodes 410 incommunication with storage manager 340; and also in communication witheach other via heartbeat monitoring distributed file system 545.

FIG. 6 is a block diagram illustrating certain functional components anda distributed file system that are configured in an illustrativeenhanced virtual server data agent which is configured as a heartbeatmonitor node.

FIG. 6A is a block diagram illustrating a logical view of VMdistribution logic 608.

FIG. 7 depicts an illustrative distributed file system 545 for VMheartbeat monitoring in system 300.

FIG. 8 depicts a template for content of an illustrative data file 712used in illustrative distributed file system 545.

FIG. 9 depicts illustrative watch processes in heartbeat monitoringdistributed file system 545 of system 300.

FIG. 10 depicts illustrative quorum 440 arrangements for heartbeatmonitor nodes.

FIG. 11 is a block diagram illustrating failover of target VMs toreplica VMs in system 1100.

FIG. 12 is a block diagram illustrating a system 1200 experiencingfailure of the entire source data center, according to an illustrativeembodiment of the present invention.

FIG. 13 is a block diagram illustrating a system 1300 for heartbeatmonitoring of virtual machines for initiating cloud-to-cloud failoverand/or failback operations, according to an illustrative embodiment ofthe present invention.

FIG. 14 is a block diagram illustrating a system 1400 for heartbeatmonitoring of VMs for initiating cloud-to-cloud failover and/or failbackoperations using an integrated storage manager and heartbeat monitornode 1410, according to an illustrative embodiment of the presentinvention.

FIG. 15 is a flow chart illustrating a method 1500 for performingvirtual machine heartbeat monitoring in a data storage managementsystem, according to an illustrative embodiment of the presentinvention.

FIG. 16 is a flow chart illustrating certain salient operations of block1504 in method 1500.

FIG. 17 is a flow chart illustrating some salient details of block 1510in method 1500.

FIG. 18 is a flow chart illustrating VM distribution rules 6122 appliedby VM distribution logic 608, when illustratively executed by the mastermonitor node, e.g., at block 1702.

FIG. 19 is a flow chart illustrating certain salient operations in block1516 of method 1500. Block 1516 is generally directed at operationsperformed by worker monitor nodes, including ping monitoring of targetVMs and confirming whether target VMs have failed.

FIG. 20 is a block diagram depicting an illustrative heartbeat packet2001 for pinging a target VM by a heartbeat monitor node designated as aworker node, e.g., 410, 1110, 1310, 1410.

FIG. 20A is a flow chart illustrating certain salient operation in block1906 of method 1500.

FIG. 21 is a flow chart illustrating certain salient operations in block1518 of method 1500.

DETAILED DESCRIPTION

Detailed descriptions and examples of systems and methods according toone or more illustrative embodiments of the present invention may befound in the section entitled HEARTBEAT MONITORING OF VIRTUAL MACHINESFOR INITIATING FAILOVER AND/OR FAILBACK OPERATIONS IN A DATA STORAGEMANAGEMENT SYSTEM, as well as in the section entitled ExampleEmbodiments, and also in FIGS. 3-21 herein. Furthermore, components andfunctionality for VM heartbeat monitoring may be configured and/orincorporated into information management systems such as those describedherein in FIGS. 1A-1H and 2A-2C.

Various embodiments described herein are intimately tied to, enabled by,and would not exist except for, computer technology. For example, VMheartbeat monitoring described herein in reference to variousembodiments cannot reasonably be performed by humans alone, without thecomputer technology upon which they are implemented.

Information Management System Overview

With the increasing importance of protecting and leveraging data,organizations simply cannot risk losing critical data. Moreover, runawaydata growth and other modern realities make protecting and managing dataincreasingly difficult. There is therefore a need for efficient,powerful, and user-friendly solutions for protecting and managing dataand for smart and efficient management of data storage. Depending on thesize of the organization, there may be many data production sourceswhich are under the purview of tens, hundreds, or even thousands ofindividuals. In the past, individuals were sometimes responsible formanaging and protecting their own data, and a patchwork of hardware andsoftware point solutions may have been used in any given organization.These solutions were often provided by different vendors and had limitedor no interoperability. Certain embodiments described herein addressthese and other shortcomings of prior approaches by implementingscalable, unified, organization-wide information management, includingdata storage management.

FIG. 1A shows one such information management system 100 (or “system100”), which generally includes combinations of hardware and softwareconfigured to protect and manage data and metadata that are generatedand used by computing devices in system 100. System 100 may be referredto in some embodiments as a “storage management system” or a “datastorage management system.” System 100 performs information managementoperations, some of which may be referred to as “storage operations” or“data storage operations,” to protect and manage the data residing inand/or managed by system 100. The organization that employs system 100may be a corporation or other business entity, non-profit organization,educational institution, household, governmental agency, or the like.

Generally, the systems and associated components described herein may becompatible with and/or provide some or all of the functionality of thesystems and corresponding components described in one or more of thefollowing U.S. patents/publications and patent applications assigned toCommvault Systems, Inc., each of which is hereby incorporated byreference in its entirety herein:

-   -   U.S. Pat. No. 7,035,880, entitled “Modular Backup and Retrieval        System Used in Conjunction With a Storage Area Network”;    -   U.S. Pat. No. 7,107,298, entitled “System And Method For        Archiving Objects In An Information Store”;    -   U.S. Pat. No. 7,246,207, entitled “System and Method for        Dynamically Performing Storage Operations in a Computer        Network”;    -   U.S. Pat. No. 7,315,923, entitled “System And Method For        Combining Data Streams In Pipelined Storage Operations In A        Storage Network”;    -   U.S. Pat. No. 7,343,453, entitled “Hierarchical Systems and        Methods for Providing a Unified View of Storage Information”;    -   U.S. Pat. No. 7,395,282, entitled “Hierarchical Backup and        Retrieval System”;    -   U.S. Pat. No. 7,529,782, entitled “System and Methods for        Performing a Snapshot and for Restoring Data”;    -   U.S. Pat. No. 7,617,262, entitled “System and Methods for        Monitoring Application Data in a Data Replication System”;    -   U.S. Pat. No. 7,734,669, entitled “Managing Copies Of Data”;    -   U.S. Pat. No. 7,747,579, entitled “Metabase for Facilitating        Data Classification”;    -   U.S. Pat. No. 8,156,086, entitled “Systems And Methods For        Stored Data Verification”;    -   U.S. Pat. No. 8,170,995, entitled “Method and System for Offline        Indexing of Content and Classifying Stored Data”;    -   U.S. Pat. No. 8,230,195, entitled “System And Method For        Performing Auxiliary Storage Operations”;    -   U.S. Pat. No. 8,285,681, entitled “Data Object Store and Server        for a Cloud Storage Environment, Including Data Deduplication        and Data Management Across Multiple Cloud Storage Sites”;    -   U.S. Pat. No. 8,307,177, entitled “Systems And Methods For        Management Of Virtualization Data”;    -   U.S. Pat. No. 8,364,652, entitled “Content-Aligned, Block-Based        Deduplication”;    -   U.S. Pat. No. 8,578,120, entitled “Block-Level Single        Instancing”;    -   U.S. Pat. No. 8,954,446, entitled “Client-Side Repository in a        Networked Deduplicated Storage System”;    -   U.S. Pat. No. 9,020,900, entitled “Distributed Deduplicated        Storage System”;    -   U.S. Pat. No. 9,098,495, entitled “Application-Aware and Remote        Single Instance Data Management”;    -   U.S. Pat. No. 9,239,687, entitled “Systems and Methods for        Retaining and Using Data Block Signatures in Data Protection        Operations”;    -   U.S. Pat. Pub. No. 2006/0224846, entitled “System and Method to        Support Single Instance Storage Operations”;    -   U.S. Pat. Pub. No. 2014/0201170, entitled “High Availability        Distributed Deduplicated Storage System”;    -   U.S. patent application Ser. No. 14/721,971, entitled        “Replication Using Deduplicated Secondary Copy Data” (applicant        docket no. 100.422.US1.145; attorney docket no. COMMV.252A);    -   U.S. Patent Application No. 62/265,339 entitled “Live        Synchronization and Management of Virtual Machines across        Computing and Virtualization Platforms and Using Live        Synchronization to Support Disaster Recovery” (applicant docket        no. 100.487.USP1.160; attorney docket no. COMMV.277PR);    -   U.S. Patent Application No. 62/273,286 entitled “Redundant and        Robust Distributed Deduplication Data Storage System” (applicant        docket no. 100.489.USP1.135; attorney docket no. COMMV.279PR);    -   U.S. Patent Application No. 62/294,920, entitled “Data        Protection Operations Based on Network Path Information”        (applicant docket no. 100.497.USP1.105; attorney docket no.        COMMV.283PR);    -   U.S. Patent Application No. 62/297,057, entitled “Data        Restoration Operations Based on Network Path Information”        (applicant docket no. 100.498.USP1.105; attorney docket no.        COMMV.284PR); and    -   U.S. Patent Application No. 62/387,384, entitled        “Application-Level Live Synchronization Across Computing        Platforms Including Synchronizing Co-Resident Applications To        Disparate Standby Destinations And Selectively Synchronizing        Some Applications And Not Others” (applicant docket no.        100.500.USP1.105; attorney docket no. COMMV.286PR).

System 100 includes computing devices and computing technologies. Forinstance, system 100 can include one or more client computing devices102 and secondary storage computing devices 106, as well as storagemanager 140 or a host computing device for it. Computing devices caninclude, without limitation, one or more: workstations, personalcomputers, desktop computers, or other types of generally fixedcomputing systems such as mainframe computers, servers, andminicomputers. Other computing devices can include mobile or portablecomputing devices, such as one or more laptops, tablet computers,personal data assistants, mobile phones (such as smartphones), and othermobile or portable computing devices such as embedded computers, set topboxes, vehicle-mounted devices, wearable computers, etc. Servers caninclude mail servers, file servers, database servers, virtual machineservers, and web servers. Any given computing device comprises one ormore processors (e.g., CPU and/or single-core or multi-core processors),as well as corresponding non-transitory computer memory (e.g.,random-access memory (RAM)) for storing computer programs which are tobe executed by the one or more processors. Other computer memory formass storage of data may be packaged/configured with the computingdevice (e.g., an internal hard disk) and/or may be external andaccessible by the computing device (e.g., network-attached storage, astorage array, etc.). In some cases, a computing device includes cloudcomputing resources, which may be implemented as virtual machines. Forinstance, one or more virtual machines may be provided to theorganization by a third-party cloud service vendor.

In some embodiments, computing devices can include one or more virtualmachine(s) running on a physical host computing device (or “hostmachine”) operated by the organization. As one example, the organizationmay use one virtual machine as a database server and another virtualmachine as a mail server, both virtual machines operating on the samehost machine. A Virtual machine (“VM”) is a software implementation of acomputer that does not physically exist and is instead instantiated inan operating system of a physical computer (or host machine) to enableapplications to execute within the VM's environment, i.e., a VM emulatesa physical computer. A VM includes an operating system and associatedvirtual resources, such as computer memory and processor(s). Ahypervisor operates between the VM and the hardware of the physical hostmachine and is generally responsible for creating and running the VMs.Hypervisors are also known in the art as virtual machine monitors or avirtual machine managers or “VMMs”, and may be implemented in software,firmware, and/or specialized hardware installed on the host machine.Examples of hypervisors include ESX Server, by VMware, Inc. of PaloAlto, Calif.; Microsoft Virtual Server and Microsoft Windows ServerHyper-V, both by Microsoft Corporation of Redmond, Wash.; Sun xVM byOracle America Inc. of Santa Clara, Calif.; and Xen by Citrix Systems,Santa Clara, Calif. The hypervisor provides resources to each virtualoperating system such as a virtual processor, virtual memory, a virtualnetwork device, and a virtual disk. Each virtual machine has one or moreassociated virtual disks. The hypervisor typically stores the data ofvirtual disks in files on the file system of the physical host machine,called virtual machine disk files (“VMDK” in VMware lingo) or virtualhard disk image files (in Microsoft lingo). For example, VMware's ESXServer provides the Virtual Machine File System (VMFS) for the storageof virtual machine disk files. A virtual machine reads data from andwrites data to its virtual disk much the way that a physical machinereads data from and writes data to a physical disk. Examples oftechniques for implementing information management in a cloud computingenvironment are described in U.S. Pat. No. 8,285,681. Examples oftechniques for implementing information management in a virtualizedcomputing environment are described in U.S. Pat. No. 8,307,177.

Information management system 100 can also include electronic datastorage devices, generally used for mass storage of data, including,e.g., primary storage devices 104 and secondary storage devices 108.Storage devices can generally be of any suitable type including, withoutlimitation, disk drives, storage arrays (e.g., storage-area network(SAN) and/or network-attached storage (NAS) technology), semiconductormemory (e.g., solid state storage devices), network attached storage(NAS) devices, tape libraries, or other magnetic, non-tape storagedevices, optical media storage devices, DNA/RNA-based memory technology,combinations of the same, etc. In some embodiments, storage devices formpart of a distributed file system. In some cases, storage devices areprovided in a cloud storage environment (e.g., a private cloud or oneoperated by a third-party vendor), whether for primary data or secondarycopies or both.

Depending on context, the term “information management system” can referto generally all of the illustrated hardware and software components inFIG. 1C, or the term may refer to only a subset of the illustratedcomponents. For instance, in some cases, system 100 generally refers toa combination of specialized components used to protect, move, manage,manipulate, analyze, and/or process data and metadata generated byclient computing devices 102. However, system 100 in some cases does notinclude the underlying components that generate and/or store primarydata 112, such as the client computing devices 102 themselves, and theprimary storage devices 104. Likewise secondary storage devices 108(e.g., a third-party provided cloud storage environment) may not be partof system 100. As an example, “information management system” or“storage management system” may sometimes refer to one or more of thefollowing components, which will be described in further detail below:storage manager, data agent, and media agent.

One or more client computing devices 102 may be part of system 100, eachclient computing device 102 having an operating system and at least oneapplication 110 and one or more accompanying data agents executingthereon; and associated with one or more primary storage devices 104storing primary data 112. Client computing device(s) 102 and primarystorage devices 104 may generally be referred to in some cases asprimary storage subsystem 117.

Client Computing Devices, Clients, and Subclients

Typically, a variety of sources in an organization produce data to beprotected and managed. As just one illustrative example, in a corporateenvironment such data sources can be employee workstations and companyservers such as a mail server, a web server, a database server, atransaction server, or the like. In system 100, data generation sourcesinclude one or more client computing devices 102. A computing devicethat has a data agent 142 installed and operating on it is generallyreferred to as a “client computing device” 102, and may include any typeof computing device, without limitation. A client computing device 102may be associated with one or more users and/or user accounts.

A “client” is a logical component of information management system 100,which may represent a logical grouping of one or more data agentsinstalled on a client computing device 102. Storage manager 140recognizes a client as a component of system 100, and in someembodiments, may automatically create a client component the first timea data agent 142 is installed on a client computing device 102. Becausedata generated by executable component(s) 110 is tracked by theassociated data agent 142 so that it may be properly protected in system100, a client may be said to generate data and to store the generateddata to primary storage, such as primary storage device 104. However,the terms “client” and “client computing device” as used herein do notimply that a client computing device 102 is necessarily configured inthe client/server sense relative to another computing device such as amail server, or that a client computing device 102 cannot be a server inits own right. As just a few examples, a client computing device 102 canbe and/or include mail servers, file servers, database servers, virtualmachine servers, and/or web servers.

Each client computing device 102 may have application(s) 110 executingthereon which generate and manipulate the data that is to be protectedfrom loss and managed in system 100. Applications 110 generallyfacilitate the operations of an organization, and can include, withoutlimitation, mail server applications (e.g., Microsoft Exchange Server),file system applications, mail client applications (e.g., MicrosoftExchange Client), database applications or database management systems(e.g., SQL, Oracle, SAP, Lotus Notes Database), word processingapplications (e.g., Microsoft Word), spreadsheet applications, financialapplications, presentation applications, graphics and/or videoapplications, browser applications, mobile applications, entertainmentapplications, and so on. Each application 110 may be accompanied by anapplication-specific data agent 142, though not all data agents 142 areapplication-specific or associated with only application. A file system,e.g., Microsoft Windows Explorer, may be considered an application 110and may be accompanied by its own data agent 142. Client computingdevices 102 can have at least one operating system (e.g., MicrosoftWindows, Mac OS X, iOS, IBM z/OS, Linux, other Unix-based operatingsystems, etc.) installed thereon, which may support or host one or morefile systems and other applications 110. In some embodiments, a virtualmachine that executes on a host client computing device 102 may beconsidered an application 110 and may be accompanied by a specific dataagent 142 (e.g., virtual server data agent).

Client computing devices 102 and other components in system 100 can beconnected to one another via one or more electronic communicationpathways 114. For example, a first communication pathway 114 maycommunicatively couple client computing device 102 and secondary storagecomputing device 106; a second communication pathway 114 maycommunicatively couple storage manager 140 and client computing device102; and a third communication pathway 114 may communicatively couplestorage manager 140 and secondary storage computing device 106, etc.(see, e.g., FIG. 1A and FIG. 1C). A communication pathway 114 caninclude one or more networks or other connection types including one ormore of the following, without limitation: the Internet, a wide areanetwork (WAN), a local area network (LAN), a Storage Area Network (SAN),a Fibre Channel (FC) connection, a Small Computer System Interface(SCSI) connection, a virtual private network (VPN), a token ring orTCP/IP based network, an intranet network, a point-to-point link, acellular network, a wireless data transmission system, a two-way cablesystem, an interactive kiosk network, a satellite network, a broadbandnetwork, a baseband network, a neural network, a mesh network, an ad hocnetwork, other appropriate computer or telecommunications networks,combinations of the same or the like. Communication pathways 114 in somecases may also include application programming interfaces (APIs)including, e.g., cloud service provider APIs, virtual machine managementAPIs, and hosted service provider APIs. The underlying infrastructure ofcommunication pathways 114 may be wired and/or wireless, analog and/ordigital, or any combination thereof; and the facilities used may beprivate, public, third-party provided, or any combination thereof,without limitation.

A “subclient” is a logical grouping of all or part of a client's primarydata 112. In general, a subclient may be defined according to how thesubclient data is to be protected as a unit in system 100. For example,a subclient may be associated with a certain storage policy. A givenclient may thus comprise several subclients, each subclient associatedwith a different storage policy. For example, some files may form afirst subclient that requires compression and deduplication and isassociated with a first storage policy. Other files of the client mayform a second subclient that requires a different retention schedule aswell as encryption, and may be associated with a different, secondstorage policy. As a result, though the primary data may be generated bythe same application 110 and may belong to one given client, portions ofthe data may be assigned to different subclients for distinct treatmentby system 100. More detail on subclients is given in regard to storagepolicies below.

Primary Data and Exemplary Primary Storage Devices

Primary data 112 is generally production data or “live” data generatedby the operating system and/or applications 110 executing on clientcomputing device 102. Primary data 112 is generally stored on primarystorage device(s) 104 and is organized via a file system operating onthe client computing device 102. Thus, client computing device(s) 102and corresponding applications 110 may create, access, modify, write,delete, and otherwise use primary data 112. Primary data 112 isgenerally in the native format of the source application 110. Primarydata 112 is an initial or first stored body of data generated by thesource application 110. Primary data 112 in some cases is createdsubstantially directly from data generated by the corresponding sourceapplication 110. It can be useful in performing certain tasks toorganize primary data 112 into units of different granularities. Ingeneral, primary data 112 can include files, directories, file systemvolumes, data blocks, extents, or any other hierarchies or organizationsof data objects. As used herein, a “data object” can refer to (i) anyfile that is currently addressable by a file system or that waspreviously addressable by the file system (e.g., an archive file),and/or to (ii) a subset of such a file (e.g., a data block, an extent,etc.). Primary data 112 may include structured data (e.g., databasefiles), unstructured data (e.g., documents), and/or semi-structureddata. See, e.g., FIG. 1B.

It can also be useful in performing certain functions of system 100 toaccess and modify metadata within primary data 112. Metadata generallyincludes information about data objects and/or characteristicsassociated with the data objects. For simplicity herein, it is to beunderstood that, unless expressly stated otherwise, any reference toprimary data 112 generally also includes its associated metadata, butreferences to metadata generally do not include the primary data.Metadata can include, without limitation, one or more of the following:the data owner (e.g., the client or user that generates the data), thelast modified time (e.g., the time of the most recent modification ofthe data object), a data object name (e.g., a file name), a data objectsize (e.g., a number of bytes of data), information about the content(e.g., an indication as to the existence of a particular search term),user-supplied tags, to/from information for email (e.g., an emailsender, recipient, etc.), creation date, file type (e.g., format orapplication type), last accessed time, application type (e.g., type ofapplication that generated the data object), location/network (e.g., acurrent, past or future location of the data object and network pathwaysto/from the data object), geographic location (e.g., GPS coordinates),frequency of change (e.g., a period in which the data object ismodified), business unit (e.g., a group or department that generates,manages or is otherwise associated with the data object), aginginformation (e.g., a schedule, such as a time period, in which the dataobject is migrated to secondary or long term storage), boot sectors,partition layouts, file location within a file folder directorystructure, user permissions, owners, groups, access control lists(ACLs), system metadata (e.g., registry information), combinations ofthe same or other similar information related to the data object. Inaddition to metadata generated by or related to file systems andoperating systems, some applications 110 and/or other components ofsystem 100 maintain indices of metadata for data objects, e.g., metadataassociated with individual email messages. The use of metadata toperform classification and other functions is described in greaterdetail below.

Primary storage devices 104 storing primary data 112 may be relativelyfast and/or expensive technology (e.g., flash storage, a disk drive, ahard-disk storage array, solid state memory, etc.), typically to supporthigh-performance live production environments. Primary data 112 may behighly changeable and/or may be intended for relatively short termretention (e.g., hours, days, or weeks). According to some embodiments,client computing device 102 can access primary data 112 stored inprimary storage device 104 by making conventional file system calls viathe operating system. Each client computing device 102 is generallyassociated with and/or in communication with one or more primary storagedevices 104 storing corresponding primary data 112. A client computingdevice 102 is said to be associated with or in communication with aparticular primary storage device 104 if it is capable of one or moreof: routing and/or storing data (e.g., primary data 112) to the primarystorage device 104, coordinating the routing and/or storing of data tothe primary storage device 104, retrieving data from the primary storagedevice 104, coordinating the retrieval of data from the primary storagedevice 104, and modifying and/or deleting data in the primary storagedevice 104. Thus, a client computing device 102 may be said to accessdata stored in an associated storage device 104.

Primary storage device 104 may be dedicated or shared. In some cases,each primary storage device 104 is dedicated to an associated clientcomputing device 102, e.g., a local disk drive. In other cases, one ormore primary storage devices 104 can be shared by multiple clientcomputing devices 102, e.g., via a local network, in a cloud storageimplementation, etc. As one example, primary storage device 104 can be astorage array shared by a group of client computing devices 102, such asEMC Clariion, EMC Symmetrix, EMC Celerra, Dell EqualLogic, IBM XIV,NetApp FAS, HP EVA, and HP 3PAR.

System 100 may also include hosted services (not shown), which may behosted in some cases by an entity other than the organization thatemploys the other components of system 100. For instance, the hostedservices may be provided by online service providers. Such serviceproviders can provide social networking services, hosted email services,or hosted productivity applications or other hosted applications such assoftware-as-a-service (SaaS), platform-as-a-service (PaaS), applicationservice providers (ASPs), cloud services, or other mechanisms fordelivering functionality via a network. As it services users, eachhosted service may generate additional data and metadata, which may bemanaged by system 100, e.g., as primary data 112. In some cases, thehosted services may be accessed using one of the applications 110. As anexample, a hosted mail service may be accessed via browser running on aclient computing device 102.

Secondary Copies and Exemplary Secondary Storage Devices

Primary data 112 stored on primary storage devices 104 may becompromised in some cases, such as when an employee deliberately oraccidentally deletes or overwrites primary data 112. Or primary storagedevices 104 can be damaged, lost, or otherwise corrupted. For recoveryand/or regulatory compliance purposes, it is therefore useful togenerate and maintain copies of primary data 112. Accordingly, system100 includes one or more secondary storage computing devices 106 and oneor more secondary storage devices 108 configured to create and store oneor more secondary copies 116 of primary data 112 including itsassociated metadata. The secondary storage computing devices 106 and thesecondary storage devices 108 may be referred to as secondary storagesubsystem 118.

Secondary copies 116 can help in search and analysis efforts and meetother information management goals as well, such as: restoring dataand/or metadata if an original version is lost (e.g., by deletion,corruption, or disaster); allowing point-in-time recovery; complyingwith regulatory data retention and electronic discovery (e-discovery)requirements; reducing utilized storage capacity in the productionsystem and/or in secondary storage; facilitating organization and searchof data; improving user access to data files across multiple computingdevices and/or hosted services; and implementing data retention andpruning policies.

A secondary copy 116 can comprise a separate stored copy of data that isderived from one or more earlier-created stored copies (e.g., derivedfrom primary data 112 or from another secondary copy 116). Secondarycopies 116 can include point-in-time data, and may be intended forrelatively long-term retention before some or all of the data is movedto other storage or discarded. In some cases, a secondary copy 116 maybe in a different storage device than other previously stored copies;and/or may be remote from other previously stored copies. Secondarycopies 116 can be stored in the same storage device as primary data 112.For example, a disk array capable of performing hardware snapshotsstores primary data 112 and creates and stores hardware snapshots of theprimary data 112 as secondary copies 116. Secondary copies 116 may bestored in relatively slow and/or lower cost storage (e.g., magnetictape). A secondary copy 116 may be stored in a backup or archive format,or in some other format different from the native source applicationformat or other format of primary data 112.

Secondary storage computing devices 106 may index secondary copies 116(e.g., using a media agent 144), enabling users to browse and restore ata later time and further enabling the lifecycle management of theindexed data. After creation of a secondary copy 116 that representscertain primary data 112, a pointer or other location indicia (e.g., astub) may be placed in primary data 112, or be otherwise associated withprimary data 112, to indicate the current location of a particularsecondary copy 116. Since an instance of a data object or metadata inprimary data 112 may change over time as it is modified by application110 (or hosted service or the operating system), system 100 may createand manage multiple secondary copies 116 of a particular data object ormetadata, each copy representing the state of the data object in primarydata 112 at a particular point in time. Moreover, since an instance of adata object in primary data 112 may eventually be deleted from primarystorage device 104 and the file system, system 100 may continue tomanage point-in-time representations of that data object, even thoughthe instance in primary data 112 no longer exists. For virtual machines,the operating system and other applications 110 of client computingdevice(s) 102 may execute within or under the management ofvirtualization software (e.g., a VMM), and the primary storage device(s)104 may comprise a virtual disk created on a physical storage device.System 100 may create secondary copies 116 of the files or other dataobjects in a virtual disk file and/or secondary copies 116 of the entirevirtual disk file itself (e.g., of an entire .vmdk file).

Secondary copies 116 are distinguishable from corresponding primary data112. First, secondary copies 116 can be stored in a different formatfrom primary data 112 (e.g., backup, archive, or other non-nativeformat). For this or other reasons, secondary copies 116 may not bedirectly usable by applications 110 or client computing device 102(e.g., via standard system calls or otherwise) without modification,processing, or other intervention by system 100 which may be referred toas “restore” operations. Secondary copies 116 may have been processed bydata agent 142 and/or media agent 144 in the course of being created(e.g., compression, deduplication, encryption, integrity markers,indexing, formatting, application-aware metadata, etc.), and thussecondary copy 116 may represent source primary data 112 withoutnecessarily being exactly identical to the source.

Second, secondary copies 116 may be stored on a secondary storage device108 that is inaccessible to application 110 running on client computingdevice 102 and/or hosted service. Some secondary copies 116 may be“offline copies,” in that they are not readily available (e.g., notmounted to tape or disk). Offline copies can include copies of data thatsystem 100 can access without human intervention (e.g., tapes within anautomated tape library, but not yet mounted in a drive), and copies thatthe system 100 can access only with some human intervention (e.g., tapeslocated at an offsite storage site).

Using Intermediate Devices for Creating Secondary Copies—SecondaryStorage Computing Devices

Creating secondary copies can be challenging when hundreds or thousandsof client computing devices 102 continually generate large volumes ofprimary data 112 to be protected. Also, there can be significantoverhead involved in the creation of secondary copies 116. Moreover,specialized programmed intelligence and/or hardware capability isgenerally needed for accessing and interacting with secondary storagedevices 108. Client computing devices 102 may interact directly with asecondary storage device 108 to create secondary copies 116, but in viewof the factors described above, this approach can negatively impact theability of client computing device 102 to serve/service application 110and produce primary data 112. Further, any given client computing device102 may not be optimized for interaction with certain secondary storagedevices 108.

Thus, system 100 may include one or more software and/or hardwarecomponents which generally act as intermediaries between clientcomputing devices 102 (that generate primary data 112) and secondarystorage devices 108 (that store secondary copies 116). In addition tooff-loading certain responsibilities from client computing devices 102,these intermediate components provide other benefits. For instance, asdiscussed further below with respect to FIG. 1D, distributing some ofthe work involved in creating secondary copies 116 can enhancescalability and improve system performance. For instance, usingspecialized secondary storage computing devices 106 and media agents 144for interfacing with secondary storage devices 108 and/or for performingcertain data processing operations can greatly improve the speed withwhich system 100 performs information management operations and can alsoimprove the capacity of the system to handle large numbers of suchoperations, while reducing the computational load on the productionenvironment of client computing devices 102. The intermediate componentscan include one or more secondary storage computing devices 106 as shownin FIG. 1A and/or one or more media agents 144. Media agents arediscussed further below (e.g., with respect to FIGS. 1C-1E). Thesespecial-purpose components of system 100 comprise specialized programmedintelligence and/or hardware capability for writing to, reading from,instructing, communicating with, or otherwise interacting with secondarystorage devices 108.

Secondary storage computing device(s) 106 can comprise any of thecomputing devices described above, without limitation. In some cases,secondary storage computing device(s) 106 also include specializedhardware componentry and/or software intelligence (e.g., specializedinterfaces) for interacting with certain secondary storage device(s) 108with which they may be specially associated.

To create a secondary copy 116 involving the copying of data fromprimary storage subsystem 117 to secondary storage subsystem 118, clientcomputing device 102 may communicate the primary data 112 to be copied(or a processed version thereof generated by a data agent 142) to thedesignated secondary storage computing device 106, via a communicationpathway 114. Secondary storage computing device 106 in turn may furtherprocess and convey the data or a processed version thereof to secondarystorage device 108. One or more secondary copies 116 may be created fromexisting secondary copies 116, such as in the case of an auxiliary copyoperation, described further below.

Exemplary Primary Data and an Exemplary Secondary Copy

FIG. 1B is a detailed view of some specific examples of primary datastored on primary storage device(s) 104 and secondary copy data storedon secondary storage device(s) 108, with other components of the systemremoved for the purposes of illustration. Stored on primary storagedevice(s) 104 are primary data 112 objects including word processingdocuments 119A-B, spreadsheets 120, presentation documents 122, videofiles 124, image files 126, email mailboxes 128 (and corresponding emailmessages 129A-C), HTML/XML or other types of markup language files 130,databases 132 and corresponding tables or other data structures133A-133C. Some or all primary data 112 objects are associated withcorresponding metadata (e.g., “Meta1-11”), which may include file systemmetadata and/or application-specific metadata. Stored on the secondarystorage device(s) 108 are secondary copy 116 data objects 134A-C whichmay include copies of or may otherwise represent corresponding primarydata 112.

Secondary copy data objects 134A-C can individually represent more thanone primary data object. For example, secondary copy data object 134Arepresents three separate primary data objects 133C, 122, and 129C(represented as 133C′, 122′, and 129C′, respectively, and accompanied bycorresponding metadata Meta11, Meta3, and Meta11, respectively).Moreover, as indicated by the prime mark (′), secondary storagecomputing devices 106 or other components in secondary storage subsystem118 may process the data received from primary storage subsystem 117 andstore a secondary copy including a transformed and/or supplementedrepresentation of a primary data object and/or metadata that isdifferent from the original format, e.g., in a compressed, encrypted,deduplicated, or other modified format. For instance, secondary storagecomputing devices 106 can generate new metadata or other informationbased on said processing, and store the newly generated informationalong with the secondary copies. Secondary copy data object 1346represents primary data objects 120, 1336, and 119A as 120′, 1336′, and119A′, respectively, accompanied by corresponding metadata Meta2,Meta10, and Meta1, respectively. Also, secondary copy data object 134Crepresents primary data objects 133A, 1196, and 129A as 133A′, 1196′,and 129A′, respectively, accompanied by corresponding metadata Meta9,Meta5, and Meta6, respectively.

Exemplary Information Management System Architecture

System 100 can incorporate a variety of different hardware and softwarecomponents, which can in turn be organized with respect to one anotherin many different configurations, depending on the embodiment. There arecritical design choices involved in specifying the functionalresponsibilities of the components and the role of each component insystem 100. Such design choices can impact how system 100 performs andadapts to data growth and other changing circumstances. FIG. 1C shows asystem 100 designed according to these considerations and includes:storage manager 140, one or more data agents 142 executing on clientcomputing device(s) 102 and configured to process primary data 112, andone or more media agents 144 executing on one or more secondary storagecomputing devices 106 for performing tasks involving secondary storagedevices 108.

Storage Manager

Storage manager 140 is a centralized storage and/or information managerthat is configured to perform certain control functions and also tostore certain critical information about system 100—hence storagemanager 140 is said to manage system 100. As noted, the number ofcomponents in system 100 and the amount of data under management can belarge. Managing the components and data is therefore a significant task,which can grow unpredictably as the number of components and data scaleto meet the needs of the organization. For these and other reasons,according to certain embodiments, responsibility for controlling system100, or at least a significant portion of that responsibility, isallocated to storage manager 140. Storage manager 140 can be adaptedindependently according to changing circumstances, without having toreplace or re-design the remainder of the system. Moreover, a computingdevice for hosting and/or operating as storage manager 140 can beselected to best suit the functions and networking needs of storagemanager 140. These and other advantages are described in further detailbelow and with respect to FIG. 1D.

Storage manager 140 may be a software module or other application hostedby a suitable computing device. In some embodiments, storage manager 140is itself a computing device that performs the functions describedherein. Storage manager 140 comprises or operates in conjunction withone or more associated data structures such as a dedicated database(e.g., management database 146), depending on the configuration. Thestorage manager 140 generally initiates, performs, coordinates, and/orcontrols storage and other information management operations performedby system 100, e.g., to protect and control primary data 112 andsecondary copies 116. In general, storage manager 140 is said to managesystem 100, which includes communicating with, instructing, andcontrolling in some circumstances components such as data agents 142 andmedia agents 144, etc.

As shown by the dashed arrowed lines 114 in FIG. 1C, storage manager 140may communicate with, instruct, and/or control some or all elements ofsystem 100, such as data agents 142 and media agents 144. In thismanner, storage manager 140 manages the operation of various hardwareand software components in system 100. In certain embodiments, controlinformation originates from storage manager 140 and status as well asindex reporting is transmitted to storage manager 140 by the managedcomponents, whereas payload data and metadata are generally communicatedbetween data agents 142 and media agents 144 (or otherwise betweenclient computing device(s) 102 and secondary storage computing device(s)106), e.g., at the direction of and under the management of storagemanager 140. Control information can generally include parameters andinstructions for carrying out information management operations, suchas, without limitation, instructions to perform a task associated withan operation, timing information specifying when to initiate a task,data path information specifying what components to communicate with oraccess in carrying out an operation, and the like. In other embodiments,some information management operations are controlled or initiated byother components of system 100 (e.g., by media agents 144 or data agents142), instead of or in combination with storage manager 140.

According to certain embodiments, storage manager 140 provides one ormore of the following functions:

-   -   communicating with data agents 142 and media agents 144,        including transmitting instructions, messages, and/or queries,        as well as receiving status reports, index information,        messages, and/or queries, and responding to same;    -   initiating execution of information management operations;    -   initiating restore and recovery operations;    -   managing secondary storage devices 108 and inventory/capacity of        the same;    -   allocating secondary storage devices 108 for secondary copy        operations;    -   reporting, searching, and/or classification of data in system        100;    -   monitoring completion of and status reporting related to        information management operations and jobs;    -   tracking movement of data within system 100;    -   tracking age information relating to secondary copies 116,        secondary storage devices 108, comparing the age information        against retention guidelines, and initiating data pruning when        appropriate;    -   tracking logical associations between components in system 100;    -   protecting metadata associated with system 100, e.g., in        management database 146;    -   implementing job management, schedule management, event        management, alert management, reporting, job history        maintenance, user security management, disaster recovery        management, and/or user interfacing for system administrators        and/or end users of system 100;    -   sending, searching, and/or viewing of log files; and    -   implementing operations management functionality.

Storage manager 140 may maintain an associated database 146 (or “storagemanager database 146” or “management database 146”) ofmanagement-related data and information management policies 148.Database 146 is stored in computer memory accessible by storage manager140. Database 146 may include a management index 150 (or “index 150”) orother data structure(s) that may store: logical associations betweencomponents of the system; user preferences and/or profiles (e.g.,preferences regarding encryption, compression, or deduplication ofprimary data or secondary copies; preferences regarding the scheduling,type, or other aspects of secondary copy or other operations; mappingsof particular information management users or user accounts to certaincomputing devices or other components, etc.; management tasks; mediacontainerization; other useful data; and/or any combination thereof. Forexample, storage manager 140 may use index 150 to track logicalassociations between media agents 144 and secondary storage devices 108and/or movement of data to/from secondary storage devices 108. Forinstance, index 150 may store data associating a client computing device102 with a particular media agent 144 and/or secondary storage device108, as specified in an information management policy 148.

Administrators and others may configure and initiate certain informationmanagement operations on an individual basis. But while this may beacceptable for some recovery operations or other infrequent tasks, it isoften not workable for implementing on-going organization-wide dataprotection and management. Thus, system 100 may utilize informationmanagement policies 148 for specifying and executing informationmanagement operations on an automated basis. Generally, an informationmanagement policy 148 can include a stored data structure or otherinformation source that specifies parameters (e.g., criteria and rules)associated with storage management or other information managementoperations. Storage manager 140 can process an information managementpolicy 148 and/or index 150 and, based on the results, identify aninformation management operation to perform, identify the appropriatecomponents in system 100 to be involved in the operation (e.g., clientcomputing devices 102 and corresponding data agents 142, secondarystorage computing devices 106 and corresponding media agents 144, etc.),establish connections to those components and/or between thosecomponents, and/or instruct and control those components to carry outthe operation. In this manner, system 100 can translate storedinformation into coordinated activity among the various computingdevices in system 100.

Management database 146 may maintain information management policies 148and associated data, although information management policies 148 can bestored in computer memory at any appropriate location outside managementdatabase 146. For instance, an information management policy 148 such asa storage policy may be stored as metadata in a media agent database 152or in a secondary storage device 108 (e.g., as an archive copy) for usein restore or other information management operations, depending on theembodiment. Information management policies 148 are described furtherbelow. According to certain embodiments, management database 146comprises a relational database (e.g., an SQL database) for trackingmetadata, such as metadata associated with secondary copy operations(e.g., what client computing devices 102 and corresponding subclientdata were protected and where the secondary copies are stored and whichmedia agent 144 performed the storage operation(s)). This and othermetadata may additionally be stored in other locations, such as atsecondary storage computing device 106 or on the secondary storagedevice 108, allowing data recovery without the use of storage manager140 in some cases. Thus, management database 146 may comprise dataneeded to kick off secondary copy operations (e.g., storage policies,schedule policies, etc.), status and reporting information aboutcompleted jobs (e.g., status and error reports on yesterday's backupjobs), and additional information sufficient to enable restore anddisaster recovery operations (e.g., media agent associations, locationindexing, content indexing, etc.).

Storage manager 140 may include a jobs agent 156, a user interface 158,and a management agent 154, all of which may be implemented asinterconnected software modules or application programs. These aredescribed further below.

Jobs agent 156 in some embodiments initiates, controls, and/or monitorsthe status of some or all information management operations previouslyperformed, currently being performed, or scheduled to be performed bysystem 100. A job is a logical grouping of information managementoperations such as daily storage operations scheduled for a certain setof subclients (e.g., generating incremental block-level backup copies116 at a certain time every day for database files in a certaingeographical location). Thus, jobs agent 156 may access informationmanagement policies 148 (e.g., in management database 146) to determinewhen, where, and how to initiate/control jobs in system 100.

Storage Manager User Interfaces

User interface 158 may include information processing and displaysoftware, such as a graphical user interface (GUI), an applicationprogram interface (API), and/or other interactive interface(s) throughwhich users and system processes can retrieve information about thestatus of information management operations or issue instructions tostorage manager 140 and other components. Via user interface 158, usersmay issue instructions to the components in system 100 regardingperformance of secondary copy and recovery operations. For example, auser may modify a schedule concerning the number of pending secondarycopy operations. As another example, a user may employ the GUI to viewthe status of pending secondary copy jobs or to monitor the status ofcertain components in system 100 (e.g., the amount of capacity left in astorage device). Storage manager 140 may track information that permitsit to select, designate, or otherwise identify content indices,deduplication databases, or similar databases or resources or data setswithin its information management cell (or another cell) to be searchedin response to certain queries. Such queries may be entered by the userby interacting with user interface 158.

Various embodiments of information management system 100 may beconfigured and/or designed to generate user interface data usable forrendering the various interactive user interfaces described. The userinterface data may be used by system 100 and/or by another system,device, and/or software program (for example, a browser program), torender the interactive user interfaces. The interactive user interfacesmay be displayed on, for example, electronic displays (including, forexample, touch-enabled displays), consoles, etc., whetherdirect-connected to storage manager 140 or communicatively coupledremotely, e.g., via an internet connection. The present disclosuredescribes various embodiments of interactive and dynamic userinterfaces, some of which may be generated by user interface agent 158,and which are the result of significant technological development. Theuser interfaces described herein may provide improved human-computerinteractions, allowing for significant cognitive and ergonomicefficiencies and advantages over previous systems, including reducedmental workloads, improved decision-making, and the like. User interface158 may operate in a single integrated view or console (not shown). Theconsole may support a reporting capability for generating a variety ofreports, which may be tailored to a particular aspect of informationmanagement.

User interfaces are not exclusive to storage manager 140 and in someembodiments a user may access information locally from a computingdevice component of system 100. For example, some information pertainingto installed data agents 142 and associated data streams may beavailable from client computing device 102. Likewise, some informationpertaining to media agents 144 and associated data streams may beavailable from secondary storage computing device 106.

Storage Manager Management Agent

Management agent 154 can provide storage manager 140 with the ability tocommunicate with other components within system 100 and/or with otherinformation management cells via network protocols and applicationprogramming interfaces (APIs) including, e.g., HTTP, HTTPS, FTP, REST,virtualization software APIs, cloud service provider APIs, and hostedservice provider APIs, without limitation. Management agent 154 alsoallows multiple information management cells to communicate with oneanother. For example, system 100 in some cases may be one informationmanagement cell in a network of multiple cells adjacent to one anotheror otherwise logically related, e.g., in a WAN or LAN. With thisarrangement, the cells may communicate with one another throughrespective management agents 154. Inter-cell communications andhierarchy is described in greater detail in e.g., U.S. Pat. No.7,343,453.

Information Management Cell

An “information management cell” (or “storage operation cell” or “cell”)may generally include a logical and/or physical grouping of acombination of hardware and software components associated withperforming information management operations on electronic data,typically one storage manager 140 and at least one data agent 142(executing on a client computing device 102) and at least one mediaagent 144 (executing on a secondary storage computing device 106). Forinstance, the components shown in FIG. 1C may together form aninformation management cell. Thus, in some configurations, a system 100may be referred to as an information management cell or a storageoperation cell. A given cell may be identified by the identity of itsstorage manager 140, which is generally responsible for managing thecell.

Multiple cells may be organized hierarchically, so that cells mayinherit properties from hierarchically superior cells or be controlledby other cells in the hierarchy (automatically or otherwise).Alternatively, in some embodiments, cells may inherit or otherwise beassociated with information management policies, preferences,information management operational parameters, or other properties orcharacteristics according to their relative position in a hierarchy ofcells. Cells may also be organized hierarchically according to function,geography, architectural considerations, or other factors useful ordesirable in performing information management operations. For example,a first cell may represent a geographic segment of an enterprise, suchas a Chicago office, and a second cell may represent a differentgeographic segment, such as a New York City office. Other cells mayrepresent departments within a particular office, e.g., human resources,finance, engineering, etc. Where delineated by function, a first cellmay perform one or more first types of information management operations(e.g., one or more first types of secondary copies at a certainfrequency), and a second cell may perform one or more second types ofinformation management operations (e.g., one or more second types ofsecondary copies at a different frequency and under different retentionrules). In general, the hierarchical information is maintained by one ormore storage managers 140 that manage the respective cells (e.g., incorresponding management database(s) 146).

Data Agents

A variety of different applications 110 can operate on a given clientcomputing device 102, including operating systems, file systems,database applications, e-mail applications, and virtual machines, justto name a few. And, as part of the process of creating and restoringsecondary copies 116, the client computing device 102 may be tasked withprocessing and preparing the primary data 112 generated by these variousapplications 110. Moreover, the nature of the processing/preparation candiffer across application types, e.g., due to inherent structural,state, and formatting differences among applications 110 and/or theoperating system of client computing device 102. Each data agent 142 istherefore advantageously configured in some embodiments to assist in theperformance of information management operations based on the type ofdata that is being protected at a client-specific and/orapplication-specific level.

Data agent 142 is a component of information system 100 and is generallydirected by storage manager 140 to participate in creating or restoringsecondary copies 116. Data agent 142 may be a software program (e.g., inthe form of a set of executable binary files) that executes on the sameclient computing device 102 as the associated application 110 that dataagent 142 is configured to protect. Data agent 142 is generallyresponsible for managing, initiating, or otherwise assisting in theperformance of information management operations in reference to itsassociated application(s) 110 and corresponding primary data 112 whichis generated/accessed by the particular application(s) 110. Forinstance, data agent 142 may take part in copying, archiving, migrating,and/or replicating of certain primary data 112 stored in the primarystorage device(s) 104. Data agent 142 may receive control informationfrom storage manager 140, such as commands to transfer copies of dataobjects and/or metadata to one or more media agents 144. Data agent 142also may compress, deduplicate, and encrypt certain primary data 112, aswell as capture application-related metadata before transmitting theprocessed data to media agent 144. Data agent 142 also may receiveinstructions from storage manager 140 to restore (or assist inrestoring) a secondary copy 116 from secondary storage device 108 toprimary storage 104, such that the restored data may be properlyaccessed by application 110 in a suitable format as though it wereprimary data 112.

Each data agent 142 may be specialized for a particular application 110.For instance, different individual data agents 142 may be designed tohandle Microsoft Exchange data, Lotus Notes data, Microsoft Windows filesystem data, Microsoft Active Directory Objects data, SQL Server data,Share Point data, Oracle database data, SAP database data, virtualmachines and/or associated data, and other types of data. A file systemdata agent, for example, may handle data files and/or other file systeminformation. If a client computing device 102 has two or more types ofdata 112, a specialized data agent 142 may be used for each data type.For example, to backup, migrate, and/or restore all of the data on aMicrosoft Exchange server, the client computing device 102 may use: (1)a Microsoft Exchange Mailbox data agent 142 to back up the Exchangemailboxes; (2) a Microsoft Exchange Database data agent 142 to back upthe Exchange databases; (3) a Microsoft Exchange Public Folder dataagent 142 to back up the Exchange Public Folders; and (4) a MicrosoftWindows File System data agent 142 to back up the file system of clientcomputing device 102. In this example, these specialized data agents 142are treated as four separate data agents 142 even though they operate onthe same client computing device 102. Other examples may include archivemanagement data agents such as a migration archiver or a compliancearchiver, Quick Recovery® agents, and continuous data replicationagents. Application-specific data agents 142 can provide improvedperformance as compared to generic agents. For instance, becauseapplication-specific data agents 142 may only handle data for a singlesoftware application, the design, operation, and performance of the dataagent 142 can be streamlined. The data agent 142 may therefore executefaster and consume less persistent storage and/or operating memory thandata agents designed to generically accommodate multiple differentsoftware applications 110.

Each data agent 142 may be configured to access data and/or metadatastored in the primary storage device(s) 104 associated with data agent142 and its host client computing device 102, and process the dataappropriately. For example, during a secondary copy operation, dataagent 142 may arrange or assemble the data and metadata into one or morefiles having a certain format (e.g., a particular backup or archiveformat) before transferring the file(s) to a media agent 144 or othercomponent. The file(s) may include a list of files or other metadata. Insome embodiments, a data agent 142 may be distributed between clientcomputing device 102 and storage manager 140 (and any other intermediatecomponents) or may be deployed from a remote location or its functionsapproximated by a remote process that performs some or all of thefunctions of data agent 142. In addition, a data agent 142 may performsome functions provided by media agent 144. Other embodiments may employone or more generic data agents 142 that can handle and process datafrom two or more different applications 110, or that can handle andprocess multiple data types, instead of or in addition to usingspecialized data agents 142. For example, one generic data agent 142 maybe used to back up, migrate and restore Microsoft Exchange Mailbox dataand Microsoft Exchange Database data, while another generic data agentmay handle Microsoft Exchange Public Folder data and Microsoft WindowsFile System data.

Media Agents

As noted, off-loading certain responsibilities from client computingdevices 102 to intermediate components such as secondary storagecomputing device(s) 106 and corresponding media agent(s) 144 can providea number of benefits including improved performance of client computingdevice 102, faster and more reliable information management operations,and enhanced scalability. In one example which will be discussed furtherbelow, media agent 144 can act as a local cache of recently-copied dataand/or metadata stored to secondary storage device(s) 108, thusimproving restore capabilities and performance for the cached data.

Media agent 144 is a component of system 100 and is generally directedby storage manager 140 in creating and restoring secondary copies 116.Whereas storage manager 140 generally manages system 100 as a whole,media agent 144 provides a portal to certain secondary storage devices108, such as by having specialized features for communicating with andaccessing certain associated secondary storage device 108. Media agent144 may be a software program (e.g., in the form of a set of executablebinary files) that executes on a secondary storage computing device 106.Media agent 144 generally manages, coordinates, and facilitates thetransmission of data between a data agent 142 (executing on clientcomputing device 102) and secondary storage device(s) 108 associatedwith media agent 144. For instance, other components in the system mayinteract with media agent 144 to gain access to data stored onassociated secondary storage device(s) 108, (e.g., to browse, read,write, modify, delete, or restore data). Moreover, media agents 144 cangenerate and store information relating to characteristics of the storeddata and/or metadata, or can generate and store other types ofinformation that generally provides insight into the contents of thesecondary storage devices 108—generally referred to as indexing of thestored secondary copies 116. Each media agent 144 may operate on adedicated secondary storage computing device 106, while in otherembodiments a plurality of media agents 144 may operate on the samesecondary storage computing device 106.

A media agent 144 may be associated with a particular secondary storagedevice 108 if that media agent 144 is capable of one or more of: routingand/or storing data to the particular secondary storage device 108;coordinating the routing and/or storing of data to the particularsecondary storage device 108; retrieving data from the particularsecondary storage device 108; coordinating the retrieval of data fromthe particular secondary storage device 108; and modifying and/ordeleting data retrieved from the particular secondary storage device108. Media agent 144 in certain embodiments is physically separate fromthe associated secondary storage device 108. For instance, a media agent144 may operate on a secondary storage computing device 106 in adistinct housing, package, and/or location from the associated secondarystorage device 108. In one example, a media agent 144 operates on afirst server computer and is in communication with a secondary storagedevice(s) 108 operating in a separate rack-mounted RAID-based system.

A media agent 144 associated with a particular secondary storage device108 may instruct secondary storage device 108 to perform an informationmanagement task. For instance, a media agent 144 may instruct a tapelibrary to use a robotic arm or other retrieval means to load or eject acertain storage media, and to subsequently archive, migrate, or retrievedata to or from that media, e.g., for the purpose of restoring data to aclient computing device 102. As another example, a secondary storagedevice 108 may include an array of hard disk drives or solid statedrives organized in a RAID configuration, and media agent 144 mayforward a logical unit number (LUN) and other appropriate information tothe array, which uses the received information to execute the desiredsecondary copy operation. Media agent 144 may communicate with asecondary storage device 108 via a suitable communications link, such asa SCSI or Fibre Channel link.

Each media agent 144 may maintain an associated media agent database152. Media agent database 152 may be stored to a disk or other storagedevice (not shown) that is local to the secondary storage computingdevice 106 on which media agent 144 executes. In other cases, mediaagent database 152 is stored separately from the host secondary storagecomputing device 106. Media agent database 152 can include, among otherthings, a media agent index 153 (see, e.g., FIG. 1C). In some cases,media agent index 153 does not form a part of and is instead separatefrom media agent database 152.

Media agent index 153 (or “index 153”) may be a data structureassociated with the particular media agent 144 that includes informationabout the stored data associated with the particular media agent andwhich may be generated in the course of performing a secondary copyoperation or a restore. Index 153 provides a fast and efficientmechanism for locating/browsing secondary copies 116 or other datastored in secondary storage devices 108 without having to accesssecondary storage device 108 to retrieve the information from there. Forinstance, for each secondary copy 116, index 153 may include metadatasuch as a list of the data objects (e.g., files/subdirectories, databaseobjects, mailbox objects, etc.), a logical path to the secondary copy116 on the corresponding secondary storage device 108, locationinformation (e.g., offsets) indicating where the data objects are storedin the secondary storage device 108, when the data objects were createdor modified, etc. Thus, index 153 includes metadata associated with thesecondary copies 116 that is readily available for use from media agent144. In some embodiments, some or all of the information in index 153may instead or additionally be stored along with secondary copies 116 insecondary storage device 108. In some embodiments, a secondary storagedevice 108 can include sufficient information to enable a “bare metalrestore,” where the operating system and/or software applications of afailed client computing device 102 or another target may beautomatically restored without manually reinstalling individual softwarepackages (including operating systems).

Because index 153 may operate as a cache, it can also be referred to asan “index cache.” In such cases, information stored in index cache 153typically comprises data that reflects certain particulars aboutrelatively recent secondary copy operations. After some triggeringevent, such as after some time elapses or index cache 153 reaches aparticular size, certain portions of index cache 153 may be copied ormigrated to secondary storage device 108, e.g., on a least-recently-usedbasis. This information may be retrieved and uploaded back into indexcache 153 or otherwise restored to media agent 144 to facilitateretrieval of data from the secondary storage device(s) 108. In someembodiments, the cached information may include format orcontainerization information related to archives or other files storedon storage device(s) 108.

In some alternative embodiments media agent 144 generally acts as acoordinator or facilitator of secondary copy operations between clientcomputing devices 102 and secondary storage devices 108, but does notactually write the data to secondary storage device 108. For instance,storage manager 140 (or media agent 144) may instruct a client computingdevice 102 and secondary storage device 108 to communicate with oneanother directly. In such a case, client computing device 102 transmitsdata directly or via one or more intermediary components to secondarystorage device 108 according to the received instructions, and viceversa. Media agent 144 may still receive, process, and/or maintainmetadata related to the secondary copy operations, i.e., may continue tobuild and maintain index 153. In these embodiments, payload data canflow through media agent 144 for the purposes of populating index 153,but not for writing to secondary storage device 108. Media agent 144and/or other components such as storage manager 140 may in some casesincorporate additional functionality, such as data classification,content indexing, deduplication, encryption, compression, and the like.Further details regarding these and other functions are described below.

Distributed, Scalable Architecture

As described, certain functions of system 100 can be distributed amongstvarious physical and/or logical components. For instance, one or more ofstorage manager 140, data agents 142, and media agents 144 may operateon computing devices that are physically separate from one another. Thisarchitecture can provide a number of benefits. For instance, hardwareand software design choices for each distributed component can betargeted to suit its particular function. The secondary computingdevices 106 on which media agents 144 operate can be tailored forinteraction with associated secondary storage devices 108 and providefast index cache operation, among other specific tasks. Similarly,client computing device(s) 102 can be selected to effectively serviceapplications 110 in order to efficiently produce and store primary data112.

Moreover, in some cases, one or more of the individual components ofinformation management system 100 can be distributed to multipleseparate computing devices. As one example, for large file systems wherethe amount of data stored in management database 146 is relativelylarge, database 146 may be migrated to or may otherwise reside on aspecialized database server (e.g., an SQL server) separate from a serverthat implements the other functions of storage manager 140. Thisdistributed configuration can provide added protection because database146 can be protected with standard database utilities (e.g., SQL logshipping or database replication) independent from other functions ofstorage manager 140. Database 146 can be efficiently replicated to aremote site for use in the event of a disaster or other data loss at theprimary site. Or database 146 can be replicated to another computingdevice within the same site, such as to a higher performance machine inthe event that a storage manager host computing device can no longerservice the needs of a growing system 100.

The distributed architecture also provides scalability and efficientcomponent utilization. FIG. 1D shows an embodiment of informationmanagement system 100 including a plurality of client computing devices102 and associated data agents 142 as well as a plurality of secondarystorage computing devices 106 and associated media agents 144.Additional components can be added or subtracted based on the evolvingneeds of system 100. For instance, depending on where bottlenecks areidentified, administrators can add additional client computing devices102, secondary storage computing devices 106, and/or secondary storagedevices 108. Moreover, where multiple fungible components are available,load balancing can be implemented to dynamically address identifiedbottlenecks. As an example, storage manager 140 may dynamically selectwhich media agents 144 and/or secondary storage devices 108 to use forstorage operations based on a processing load analysis of media agents144 and/or secondary storage devices 108, respectively.

Where system 100 includes multiple media agents 144 (see, e.g., FIG.1D), a first media agent 144 may provide failover functionality for asecond failed media agent 144. In addition, media agents 144 can bedynamically selected to provide load balancing. Each client computingdevice 102 can communicate with, among other components, any of themedia agents 144, e.g., as directed by storage manager 140. And eachmedia agent 144 may communicate with, among other components, any ofsecondary storage devices 108, e.g., as directed by storage manager 140.Thus, operations can be routed to secondary storage devices 108 in adynamic and highly flexible manner, to provide load balancing, failover,etc. Further examples of scalable systems capable of dynamic storageoperations, load balancing, and failover are provided in U.S. Pat. No.7,246,207.

While distributing functionality amongst multiple computing devices canhave certain advantages, in other contexts it can be beneficial toconsolidate functionality on the same computing device. In alternativeconfigurations, certain components may reside and execute on the samecomputing device. As such, in other embodiments, one or more of thecomponents shown in FIG. 1C may be implemented on the same computingdevice. In one configuration, a storage manager 140, one or more dataagents 142, and/or one or more media agents 144 are all implemented onthe same computing device. In other embodiments, one or more data agents142 and one or more media agents 144 are implemented on the samecomputing device, while storage manager 140 is implemented on a separatecomputing device, etc. without limitation.

Exemplary Types of Information Management Operations, Including StorageOperations

In order to protect and leverage stored data, system 100 can beconfigured to perform a variety of information management operations,which may also be referred to in some cases as storage managementoperations or storage operations. These operations can generally include(i) data movement operations, (ii) processing and data manipulationoperations, and (iii) analysis, reporting, and management operations.

Data Movement Operations, Including Secondary Copy Operations

Data movement operations are generally storage operations that involvethe copying or migration of data between different locations in system100. For example, data movement operations can include operations inwhich stored data is copied, migrated, or otherwise transferred from oneor more first storage devices to one or more second storage devices,such as from primary storage device(s) 104 to secondary storagedevice(s) 108, from secondary storage device(s) 108 to differentsecondary storage device(s) 108, from secondary storage devices 108 toprimary storage devices 104, or from primary storage device(s) 104 todifferent primary storage device(s) 104, or in some cases within thesame primary storage device 104 such as within a storage array.

Data movement operations can include by way of example, backupoperations, archive operations, information lifecycle managementoperations such as hierarchical storage management operations,replication operations (e.g., continuous data replication), snapshotoperations, deduplication or single-instancing operations, auxiliarycopy operations, disaster-recovery copy operations, and the like. Aswill be discussed, some of these operations do not necessarily createdistinct copies. Nonetheless, some or all of these operations aregenerally referred to as “secondary copy operations” for simplicity,because they involve secondary copies. Data movement also comprisesrestoring secondary copies.

Backup Operations

A backup operation creates a copy of a version of primary data 112 at aparticular point in time (e.g., one or more files or other data units).Each subsequent backup copy 116 (which is a form of secondary copy 116)may be maintained independently of the first. A backup generallyinvolves maintaining a version of the copied primary data 112 as well asbackup copies 116. Further, a backup copy in some embodiments isgenerally stored in a form that is different from the native format,e.g., a backup format. This contrasts to the version in primary data 112which may instead be stored in a format native to the sourceapplication(s) 110. In various cases, backup copies can be stored in aformat in which the data is compressed, encrypted, deduplicated, and/orotherwise modified from the original native application format. Forexample, a backup copy may be stored in a compressed backup format thatfacilitates efficient long-term storage. Backup copies 116 can haverelatively long retention periods as compared to primary data 112, whichis generally highly changeable. Backup copies 116 may be stored on mediawith slower retrieval times than primary storage device 104. Some backupcopies may have shorter retention periods than some other types ofsecondary copies 116, such as archive copies (described below). Backupsmay be stored at an offsite location.

Backup operations can include full backups, differential backups,incremental backups, “synthetic full” backups, and/or creating a“reference copy.” A full backup (or “standard full backup”) in someembodiments is generally a complete image of the data to be protected.However, because full backup copies can consume a relatively largeamount of storage, it can be useful to use a full backup copy as abaseline and only store changes relative to the full backup copyafterwards.

A differential backup operation (or cumulative incremental backupoperation) tracks and stores changes that occurred since the last fullbackup. Differential backups can grow quickly in size, but can restorerelatively efficiently because a restore can be completed in some casesusing only the full backup copy and the latest differential copy.

An incremental backup operation generally tracks and stores changessince the most recent backup copy of any type, which can greatly reducestorage utilization. In some cases, however, restoring can be lengthycompared to full or differential backups because completing a restoreoperation may involve accessing a full backup in addition to multipleincremental backups.

Synthetic full backups generally consolidate data without directlybacking up data from the client computing device. A synthetic fullbackup is created from the most recent full backup (i.e., standard orsynthetic) and subsequent incremental and/or differential backups. Theresulting synthetic full backup is identical to what would have beencreated had the last backup for the subclient been a standard fullbackup. Unlike standard full, incremental, and differential backups,however, a synthetic full backup does not actually transfer data fromprimary storage to the backup media, because it operates as a backupconsolidator. A synthetic full backup extracts the index data of eachparticipating subclient. Using this index data and the previously backedup user data images, it builds new full backup images (e.g., bitmaps),one for each subclient. The new backup images consolidate the index anduser data stored in the related incremental, differential, and previousfull backups into a synthetic backup file that fully represents thesubclient (e.g., via pointers) but does not comprise all its constituentdata.

Any of the above types of backup operations can be at the volume level,file level, or block level. Volume level backup operations generallyinvolve copying of a data volume (e.g., a logical disk or partition) asa whole. In a file-level backup, information management system 100generally tracks changes to individual files and includes copies offiles in the backup copy. For block-level backups, files are broken intoconstituent blocks, and changes are tracked at the block level. Uponrestore, system 100 reassembles the blocks into files in a transparentfashion. Far less data may actually be transferred and copied tosecondary storage devices 108 during a file-level copy than avolume-level copy. Likewise, a block-level copy may transfer less datathan a file-level copy, resulting in faster execution. However,restoring a relatively higher-granularity copy can result in longerrestore times. For instance, when restoring a block-level copy, theprocess of locating and retrieving constituent blocks can sometimes takelonger than restoring file-level backups.

A reference copy may comprise copy(ies) of selected objects from backedup data, typically to help organize data by keeping contextualinformation from multiple sources together, and/or help retain specificdata for a longer period of time, such as for legal hold needs. Areference copy generally maintains data integrity, and when the data isrestored, it may be viewed in the same format as the source data. Insome embodiments, a reference copy is based on a specialized client,individual subclient and associated information management policies(e.g., storage policy, retention policy, etc.) that are administeredwithin system 100.

Archive Operations

Because backup operations generally involve maintaining a version of thecopied primary data 112 and also maintaining backup copies in secondarystorage device(s) 108, they can consume significant storage capacity. Toreduce storage consumption, an archive operation according to certainembodiments creates an archive copy 116 by both copying and removingsource data. Or, seen another way, archive operations can involve movingsome or all of the source data to the archive destination. Thus, datasatisfying criteria for removal (e.g., data of a threshold age or size)may be removed from source storage. The source data may be primary data112 or a secondary copy 116, depending on the situation. As with backupcopies, archive copies can be stored in a format in which the data iscompressed, encrypted, deduplicated, and/or otherwise modified from theformat of the original application or source copy. In addition, archivecopies may be retained for relatively long periods of time (e.g., years)and, in some cases are never deleted. In certain embodiments, archivecopies may be made and kept for extended periods in order to meetcompliance regulations.

Archiving can also serve the purpose of freeing up space in primarystorage device(s) 104 and easing the demand on computational resourceson client computing device 102. Similarly, when a secondary copy 116 isarchived, the archive copy can therefore serve the purpose of freeing upspace in the source secondary storage device(s) 108. Examples of dataarchiving operations are provided in U.S. Pat. No. 7,107,298.

Snapshot Operations

Snapshot operations can provide a relatively lightweight, efficientmechanism for protecting data. From an end-user viewpoint, a snapshotmay be thought of as an “instant” image of primary data 112 at a givenpoint in time, and may include state and/or status information relativeto an application 110 that creates/manages primary data 112. In oneembodiment, a snapshot may generally capture the directory structure ofan object in primary data 112 such as a file or volume or other data setat a particular moment in time and may also preserve file attributes andcontents. A snapshot in some cases is created relatively quickly, e.g.,substantially instantly, using a minimum amount of file space, but maystill function as a conventional file system backup.

A “hardware snapshot” (or “hardware-based snapshot”) operation occurswhere a target storage device (e.g., a primary storage device 104 or asecondary storage device 108) performs the snapshot operation in aself-contained fashion, substantially independently, using hardware,firmware and/or software operating on the storage device itself. Forinstance, the storage device may perform snapshot operations generallywithout intervention or oversight from any of the other components ofthe system 100, e.g., a storage array may generate an “array-created”hardware snapshot and may also manage its storage, integrity,versioning, etc. In this manner, hardware snapshots can off-load othercomponents of system 100 from snapshot processing. An array may receivea request from another component to take a snapshot and then proceed toexecute the “hardware snapshot” operations autonomously, preferablyreporting success to the requesting component.

A “software snapshot” (or “software-based snapshot”) operation, on theother hand, occurs where a component in system 100 (e.g., clientcomputing device 102, etc.) implements a software layer that manages thesnapshot operation via interaction with the target storage device. Forinstance, the component executing the snapshot management software layermay derive a set of pointers and/or data that represents the snapshot.The snapshot management software layer may then transmit the same to thetarget storage device, along with appropriate instructions for writingthe snapshot. One example of a software snapshot product is MicrosoftVolume Snapshot Service (VSS), which is part of the Microsoft Windowsoperating system.

Some types of snapshots do not actually create another physical copy ofall the data as it existed at the particular point in time, but maysimply create pointers that map files and directories to specific memorylocations (e.g., to specific disk blocks) where the data resides as itexisted at the particular point in time. For example, a snapshot copymay include a set of pointers derived from the file system or from anapplication. In some other cases, the snapshot may be created at theblock-level, such that creation of the snapshot occurs without awarenessof the file system. Each pointer points to a respective stored datablock, so that collectively, the set of pointers reflect the storagelocation and state of the data object (e.g., file(s) or volume(s) ordata set(s)) at the point in time when the snapshot copy was created.

An initial snapshot may use only a small amount of disk space needed torecord a mapping or other data structure representing or otherwisetracking the blocks that correspond to the current state of the filesystem. Additional disk space is usually required only when files anddirectories change later on. Furthermore, when files change, typicallyonly the pointers which map to blocks are copied, not the blocksthemselves. For example for “copy-on-write” snapshots, when a blockchanges in primary storage, the block is copied to secondary storage orcached in primary storage before the block is overwritten in primarystorage, and the pointer to that block is changed to reflect the newlocation of that block. The snapshot mapping of file system data mayalso be updated to reflect the changed block(s) at that particular pointin time. In some other cases, a snapshot includes a full physical copyof all or substantially all of the data represented by the snapshot.Further examples of snapshot operations are provided in U.S. Pat. No.7,529,782. A snapshot copy in many cases can be made quickly and withoutsignificantly impacting primary computing resources because largeamounts of data need not be copied or moved. In some embodiments, asnapshot may exist as a virtual file system, parallel to the actual filesystem. Users in some cases gain read-only access to the record of filesand directories of the snapshot. By electing to restore primary data 112from a snapshot taken at a given point in time, users may also returnthe current file system to the state of the file system that existedwhen the snapshot was taken.

Replication Operations

Replication is another type of secondary copy operation. Some types ofsecondary copies 116 periodically capture images of primary data 112 atparticular points in time (e.g., backups, archives, and snapshots).However, it can also be useful for recovery purposes to protect primarydata 112 in a more continuous fashion, by replicating primary data 112substantially as changes occur. In some cases a replication copy can bea mirror copy, for instance, where changes made to primary data 112 aremirrored or substantially immediately copied to another location (e.g.,to secondary storage device(s) 108). By copying each write operation tothe replication copy, two storage systems are kept synchronized orsubstantially synchronized so that they are virtually identical atapproximately the same time. Where entire disk volumes are mirrored,however, mirroring can require significant amount of storage space andutilizes a large amount of processing resources.

According to some embodiments, secondary copy operations are performedon replicated data that represents a recoverable state, or “known goodstate” of a particular application running on the source system. Forinstance, in certain embodiments, known good replication copies may beviewed as copies of primary data 112. This feature allows the system todirectly access, copy, restore, back up, or otherwise manipulate thereplication copies as if they were the “live” primary data 112. This canreduce access time, storage utilization, and impact on sourceapplications 110, among other benefits. Based on known good stateinformation, system 100 can replicate sections of application data thatrepresent a recoverable state rather than rote copying of blocks ofdata. Examples of replication operations (e.g., continuous datareplication) are provided in U.S. Pat. No. 7,617,262.

Deduplication/Single-Instancing Operations

Deduplication or single-instance storage is useful to reduce the amountof non-primary data. For instance, some or all of the above-describedsecondary copy operations can involve deduplication in some fashion. Newdata is read, broken down into data portions of a selected granularity(e.g., sub-file level blocks, files, etc.), compared with correspondingportions that are already in secondary storage, and only new/changedportions are stored. Portions that already exist are represented aspointers to the already-stored data. Thus, a deduplicated secondary copy116 may comprise actual data portions copied from primary data 112 andmay further comprise pointers to already-stored data, which is generallymore storage-efficient than a full copy.

In order to streamline the comparison process, system 100 may calculateand/or store signatures (e.g., hashes or cryptographically unique IDs)corresponding to the individual source data portions and compare thesignatures to already-stored data signatures, instead of comparingentire data portions. In some cases, only a single instance of each dataportion is stored, and deduplication operations may therefore bereferred to interchangeably as “single-instancing” operations. Dependingon the implementation, however, deduplication operations can store morethan one instance of certain data portions, yet still significantlyreduce stored-data redundancy. Depending on the embodiment,deduplication portions such as data blocks can be of fixed or variablelength. Using variable length blocks can enhance deduplication byresponding to changes in the data stream, but can involve more complexprocessing. In some cases, system 100 utilizes a technique fordynamically aligning deduplication blocks based on changing content inthe data stream, as described in U.S. Pat. No. 8,364,652.

System 100 can deduplicate in a variety of manners at a variety oflocations. For instance, in some embodiments, system 100 implements“target-side” deduplication by deduplicating data at the media agent 144after being received from data agent 142. In some such cases, mediaagents 144 are generally configured to manage the deduplication process.For instance, one or more of the media agents 144 maintain acorresponding deduplication database that stores deduplicationinformation (e.g., datablock signatures). Examples of such aconfiguration are provided in U.S. Pat. No. 9,020,900. Instead of or incombination with “target-side” deduplication, “source-side” (or“client-side”) deduplication can also be performed, e.g., to reduce theamount of data to be transmitted by data agent 142 to media agent 144.Storage manager 140 may communicate with other components within system100 via network protocols and cloud service provider APIs to facilitatecloud-based deduplication/single instancing, as exemplified in U.S. Pat.No. 8,954,446. Some other deduplication/single instancing techniques aredescribed in U.S. Pat. Pub. No. 2006/0224846 and in U.S. Pat. No.9,098,495.

Information Lifecycle Management and Hierarchical Storage Management

In some embodiments, files and other data over their lifetime move frommore expensive quick-access storage to less expensive slower-accessstorage. Operations associated with moving data through various tiers ofstorage are sometimes referred to as information lifecycle management(ILM) operations.

One type of ILM operation is a hierarchical storage management (HSM)operation, which generally automatically moves data between classes ofstorage devices, such as from high-cost to low-cost storage devices. Forinstance, an HSM operation may involve movement of data from primarystorage devices 104 to secondary storage devices 108, or between tiersof secondary storage devices 108. With each tier, the storage devicesmay be progressively cheaper, have relatively slower access/restoretimes, etc. For example, movement of data between tiers may occur asdata becomes less important over time. In some embodiments, an HSMoperation is similar to archiving in that creating an HSM copy may(though not always) involve deleting some of the source data, e.g.,according to one or more criteria related to the source data. Forexample, an HSM copy may include primary data 112 or a secondary copy116 that exceeds a given size threshold or a given age threshold. Often,and unlike some types of archive copies, HSM data that is removed oraged from the source is replaced by a logical reference pointer or stub.The reference pointer or stub can be stored in the primary storagedevice 104 or other source storage device, such as a secondary storagedevice 108 to replace the deleted source data and to point to orotherwise indicate the new location in (another) secondary storagedevice 108.

For example, files are generally moved between higher and lower coststorage depending on how often the files are accessed. When a userrequests access to HSM data that has been removed or migrated, system100 uses the stub to locate the data and makes recovery of the dataappear transparent, even though the HSM data may be stored at a locationdifferent from other source data. In this manner, the data appears tothe user (e.g., in file system browsing windows and the like) as if itstill resides in the source location (e.g., in a primary storage device104). The stub may include metadata associated with the correspondingdata, so that a file system and/or application can provide someinformation about the data object and/or a limited-functionality version(e.g., a preview) of the data object.

An HSM copy may be stored in a format other than the native applicationformat (e.g., compressed, encrypted, deduplicated, and/or otherwisemodified). In some cases, copies which involve the removal of data fromsource storage and the maintenance of stub or other logical referenceinformation on source storage may be referred to generally as “onlinearchive copies.” On the other hand, copies which involve the removal ofdata from source storage without the maintenance of stub or otherlogical reference information on source storage may be referred to as“off-line archive copies.” Examples of HSM and ILM techniques areprovided in U.S. Pat. No. 7,343,453.

Auxiliary Copy Operations

An auxiliary copy is generally a copy of an existing secondary copy 116.For instance, an initial secondary copy 116 may be derived from primarydata 112 or from data residing in secondary storage subsystem 118,whereas an auxiliary copy is generated from the initial secondary copy116. Auxiliary copies provide additional standby copies of data and mayreside on different secondary storage devices 108 than the initialsecondary copies 116. Thus, auxiliary copies can be used for recoverypurposes if initial secondary copies 116 become unavailable. Exemplaryauxiliary copy techniques are described in further detail in U.S. Pat.No. 8,230,195.

Disaster-Recovery Copy Operations

System 100 may also make and retain disaster recovery copies, often assecondary, high-availability disk copies. System 100 may createsecondary copies and store them at disaster recovery locations usingauxiliary copy or replication operations, such as continuous datareplication technologies. Depending on the particular data protectiongoals, disaster recovery locations can be remote from the clientcomputing devices 102 and primary storage devices 104, remote from someor all of the secondary storage devices 108, or both.

Data Manipulation, Including Encryption and Compression

Data manipulation and processing may include encryption and compressionas well as integrity marking and checking, formatting for transmission,formatting for storage, etc. Data may be manipulated “client-side” bydata agent 142 as well as “target-side” by media agent 144 in the courseof creating secondary copy 116, or conversely in the course of restoringdata from secondary to primary.

Encryption Operations

System 100 in some cases is configured to process data (e.g., files orother data objects, primary data 112, secondary copies 116, etc.),according to an appropriate encryption algorithm (e.g., Blowfish,Advanced Encryption Standard (AES), Triple Data Encryption Standard(3-DES), etc.) to limit access and provide data security. System 100 insome cases encrypts the data at the client level, such that clientcomputing devices 102 (e.g., data agents 142) encrypt the data prior totransferring it to other components, e.g., before sending the data tomedia agents 144 during a secondary copy operation. In such cases,client computing device 102 may maintain or have access to an encryptionkey or passphrase for decrypting the data upon restore. Encryption canalso occur when media agent 144 creates auxiliary copies or archivecopies. Encryption may be applied in creating a secondary copy 116 of apreviously unencrypted secondary copy 116, without limitation. Infurther embodiments, secondary storage devices 108 can implementbuilt-in, high performance hardware-based encryption.

Compression Operations

Similar to encryption, system 100 may also or alternatively compressdata in the course of generating a secondary copy 116. Compressionencodes information such that fewer bits are needed to represent theinformation as compared to the original representation. Compressiontechniques are well known in the art. Compression operations may applyone or more data compression algorithms. Compression may be applied increating a secondary copy 116 of a previously uncompressed secondarycopy, e.g., when making archive copies or disaster recovery copies. Theuse of compression may result in metadata that specifies the nature ofthe compression, so that data may be uncompressed on restore ifappropriate.

Data Analysis, Reporting, and Management Operations

Data analysis, reporting, and management operations can differ from datamovement operations in that they do not necessarily involve copying,migration or other transfer of data between different locations in thesystem. For instance, data analysis operations may involve processing(e.g., offline processing) or modification of already stored primarydata 112 and/or secondary copies 116. However, in some embodiments dataanalysis operations are performed in conjunction with data movementoperations. Some data analysis operations include content indexingoperations and classification operations which can be useful inleveraging data under management to enhance search and other features.

Classification Operations/Content Indexing

In some embodiments, information management system 100 analyzes andindexes characteristics, content, and metadata associated with primarydata 112 (“online content indexing”) and/or secondary copies 116(“off-line content indexing”). Content indexing can identify files orother data objects based on content (e.g., user-defined keywords orphrases, other keywords/phrases that are not defined by a user, etc.),and/or metadata (e.g., email metadata such as “to,” “from,” “cc,” “bcc,”attachment name, received time, etc.). Content indexes may be searchedand search results may be restored.

System 100 generally organizes and catalogues the results into a contentindex, which may be stored within media agent database 152, for example.The content index can also include the storage locations of or pointerreferences to indexed data in primary data 112 and/or secondary copies116. Results may also be stored elsewhere in system 100 (e.g., inprimary storage device 104 or in secondary storage device 108). Suchcontent index data provides storage manager 140 or other components withan efficient mechanism for locating primary data 112 and/or secondarycopies 116 of data objects that match particular criteria, thus greatlyincreasing the search speed capability of system 100. For instance,search criteria can be specified by a user through user interface 158 ofstorage manager 140. Moreover, when system 100 analyzes data and/ormetadata in secondary copies 116 to create an “off-line content index,”this operation has no significant impact on the performance of clientcomputing devices 102 and thus does not take a toll on the productionenvironment. Examples of content indexing techniques are provided inU.S. Pat. No. 8,170,995.

One or more components, such as a content index engine, can beconfigured to scan data and/or associated metadata for classificationpurposes to populate a database (or other data structure) ofinformation, which can be referred to as a “data classificationdatabase” or a “metabase.” Depending on the embodiment, the dataclassification database(s) can be organized in a variety of differentways, including centralization, logical sub-divisions, and/or physicalsub-divisions. For instance, one or more data classification databasesmay be associated with different subsystems or tiers within system 100.As an example, there may be a first metabase associated with primarystorage subsystem 117 and a second metabase associated with secondarystorage subsystem 118. In other cases, metabase(s) may be associatedwith individual components, e.g., client computing devices 102 and/ormedia agents 144. In some embodiments, a data classification databasemay reside as one or more data structures within management database146, may be otherwise associated with storage manager 140, and/or mayreside as a separate component. In some cases, metabase(s) may beincluded in separate database(s) and/or on separate storage device(s)from primary data 112 and/or secondary copies 116, such that operationsrelated to the metabase(s) do not significantly impact performance onother components of system 100. In other cases, metabase(s) may bestored along with primary data 112 and/or secondary copies 116. Files orother data objects can be associated with identifiers (e.g., tagentries, etc.) to facilitate searches of stored data objects. Among anumber of other benefits, the metabase can also allow efficient,automatic identification of files or other data objects to associatewith secondary copy or other information management operations. Forinstance, a metabase can dramatically improve the speed with whichsystem 100 can search through and identify data as compared to otherapproaches that involve scanning an entire file system. Examples ofmetabases and data classification operations are provided in U.S. Pat.Nos. 7,734,669 and 7,747,579.

Management and Reporting Operations

Certain embodiments leverage the integrated ubiquitous nature of system100 to provide useful system-wide management and reporting. Operationsmanagement can generally include monitoring and managing the health andperformance of system 100 by, without limitation, performing errortracking, generating granular storage/performance metrics (e.g., jobsuccess/failure information, deduplication efficiency, etc.), generatingstorage modeling and costing information, and the like. As an example,storage manager 140 or another component in system 100 may analyzetraffic patterns and suggest and/or automatically route data to minimizecongestion. In some embodiments, the system can generate predictionsrelating to storage operations or storage operation information. Suchpredictions, which may be based on a trending analysis, may predictvarious network operations or resource usage, such as network trafficlevels, storage media use, use of bandwidth of communication links, useof media agent components, etc. Further examples of traffic analysis,trend analysis, prediction generation, and the like are described inU.S. Pat. No. 7,343,453.

In some configurations having a hierarchy of storage operation cells, amaster storage manager 140 may track the status of subordinate cells,such as the status of jobs, system components, system resources, andother items, by communicating with storage managers 140 (or othercomponents) in the respective storage operation cells. Moreover, themaster storage manager 140 may also track status by receiving periodicstatus updates from the storage managers 140 (or other components) inthe respective cells regarding jobs, system components, systemresources, and other items. In some embodiments, a master storagemanager 140 may store status information and other information regardingits associated storage operation cells and other system information inits management database 146 and/or index 150 (or in another location).The master storage manager 140 or other component may also determinewhether certain storage-related or other criteria are satisfied, and mayperform an action or trigger event (e.g., data migration) in response tothe criteria being satisfied, such as where a storage threshold is metfor a particular volume, or where inadequate protection exists forcertain data. For instance, data from one or more storage operationcells is used to dynamically and automatically mitigate recognizedrisks, and/or to advise users of risks or suggest actions to mitigatethese risks. For example, an information management policy may specifycertain requirements (e.g., that a storage device should maintain acertain amount of free space, that secondary copies should occur at aparticular interval, that data should be aged and migrated to otherstorage after a particular period, that data on a secondary volumeshould always have a certain level of availability and be restorablewithin a given time period, that data on a secondary volume may bemirrored or otherwise migrated to a specified number of other volumes,etc.). If a risk condition or other criterion is triggered, the systemmay notify the user of these conditions and may suggest (orautomatically implement) a mitigation action to address the risk. Forexample, the system may indicate that data from a primary copy 112should be migrated to a secondary storage device 108 to free up space onprimary storage device 104. Examples of the use of risk factors andother triggering criteria are described in U.S. Pat. No. 7,343,453.

In some embodiments, system 100 may also determine whether a metric orother indication satisfies particular storage criteria sufficient toperform an action. For example, a storage policy or other definitionmight indicate that a storage manager 140 should initiate a particularaction if a storage metric or other indication drops below or otherwisefails to satisfy specified criteria such as a threshold of dataprotection. In some embodiments, risk factors may be quantified intocertain measurable service or risk levels. For example, certainapplications and associated data may be considered to be more importantrelative to other data and services. Financial compliance data, forexample, may be of greater importance than marketing materials, etc.Network administrators may assign priority values or “weights” tocertain data and/or applications corresponding to the relativeimportance. The level of compliance of secondary copy operationsspecified for these applications may also be assigned a certain value.Thus, the health, impact, and overall importance of a service may bedetermined, such as by measuring the compliance value and calculatingthe product of the priority value and the compliance value to determinethe “service level” and comparing it to certain operational thresholdsto determine whether it is acceptable. Further examples of the servicelevel determination are provided in U.S. Pat. No. 7,343,453.

System 100 may additionally calculate data costing and data availabilityassociated with information management operation cells. For instance,data received from a cell may be used in conjunction withhardware-related information and other information about system elementsto determine the cost of storage and/or the availability of particulardata. Exemplary information generated could include how fast aparticular department is using up available storage space, how long datawould take to recover over a particular pathway from a particularsecondary storage device, costs over time, etc. Moreover, in someembodiments, such information may be used to determine or predict theoverall cost associated with the storage of certain information. Thecost associated with hosting a certain application may be based, atleast in part, on the type of media on which the data resides, forexample. Storage devices may be assigned to a particular costcategories, for example. Further examples of costing techniques aredescribed in U.S. Pat. No. 7,343,453.

Any of the above types of information (e.g., information related totrending, predictions, job, cell or component status, risk, servicelevel, costing, etc.) can generally be provided to users via userinterface 158 in a single integrated view or console (not shown). Reporttypes may include: scheduling, event management, media management anddata aging. Available reports may also include backup history, dataaging history, auxiliary copy history, job history, library and drive,media in library, restore history, and storage policy, etc., withoutlimitation. Such reports may be specified and created at a certain pointin time as a system analysis, forecasting, or provisioning tool.Integrated reports may also be generated that illustrate storage andperformance metrics, risks and storage costing information. Moreover,users may create their own reports based on specific needs. Userinterface 158 can include an option to graphically depict the variouscomponents in the system using appropriate icons. As one example, userinterface 158 may provide a graphical depiction of primary storagedevices 104, secondary storage devices 108, data agents 142 and/or mediaagents 144, and their relationship to one another in system 100.

In general, the operations management functionality of system 100 canfacilitate planning and decision-making. For example, in someembodiments, a user may view the status of some or all jobs as well asthe status of each component of information management system 100. Usersmay then plan and make decisions based on this data. For instance, auser may view high-level information regarding secondary copy operationsfor system 100, such as job status, component status, resource status(e.g., communication pathways, etc.), and other information. The usermay also drill down or use other means to obtain more detailedinformation regarding a particular component, job, or the like. Furtherexamples are provided in U.S. Pat. No. 7,343,453.

System 100 can also be configured to perform system-wide e-discoveryoperations in some embodiments. In general, e-discovery operationsprovide a unified collection and search capability for data in thesystem, such as data stored in secondary storage devices 108 (e.g.,backups, archives, or other secondary copies 116). For example, system100 may construct and maintain a virtual repository for data stored insystem 100 that is integrated across source applications 110, differentstorage device types, etc. According to some embodiments, e-discoveryutilizes other techniques described herein, such as data classificationand/or content indexing.

Information Management Policies

An information management policy 148 can include a data structure orother information source that specifies a set of parameters (e.g.,criteria and rules) associated with secondary copy and/or otherinformation management operations.

One type of information management policy 148 is a “storage policy.”According to certain embodiments, a storage policy generally comprises adata structure or other information source that defines (or includesinformation sufficient to determine) a set of preferences or othercriteria for performing information management operations. Storagepolicies can include one or more of the following: (1) what data will beassociated with the storage policy, e.g., subclient; (2) a destinationto which the data will be stored; (3) datapath information specifyinghow the data will be communicated to the destination; (4) the type ofsecondary copy operation to be performed; and (5) retention informationspecifying how long the data will be retained at the destination (see,e.g., FIG. 1E). Data associated with a storage policy can be logicallyorganized into subclients, which may represent primary data 112 and/orsecondary copies 116. A subclient may represent static or dynamicassociations of portions of a data volume. Subclients may representmutually exclusive portions. Thus, in certain embodiments, a portion ofdata may be given a label and the association is stored as a staticentity in an index, database or other storage location. Subclients mayalso be used as an effective administrative scheme of organizing dataaccording to data type, department within the enterprise, storagepreferences, or the like. Depending on the configuration, subclients cancorrespond to files, folders, virtual machines, databases, etc. In oneexemplary scenario, an administrator may find it preferable to separatee-mail data from financial data using two different subclients.

A storage policy can define where data is stored by specifying a targetor destination storage device (or group of storage devices). Forinstance, where the secondary storage device 108 includes a group ofdisk libraries, the storage policy may specify a particular disk libraryfor storing the subclients associated with the policy. As anotherexample, where the secondary storage devices 108 include one or moretape libraries, the storage policy may specify a particular tape libraryfor storing the subclients associated with the storage policy, and mayalso specify a drive pool and a tape pool defining a group of tapedrives and a group of tapes, respectively, for use in storing thesubclient data. While information in the storage policy can bestatically assigned in some cases, some or all of the information in thestorage policy can also be dynamically determined based on criteria setforth in the storage policy. For instance, based on such criteria, aparticular destination storage device(s) or other parameter of thestorage policy may be determined based on characteristics associatedwith the data involved in a particular secondary copy operation, deviceavailability (e.g., availability of a secondary storage device 108 or amedia agent 144), network status and conditions (e.g., identifiedbottlenecks), user credentials, and the like.

Datapath information can also be included in the storage policy. Forinstance, the storage policy may specify network pathways and componentsto utilize when moving the data to the destination storage device(s). Insome embodiments, the storage policy specifies one or more media agents144 for conveying data associated with the storage policy between thesource and destination. A storage policy can also specify the type(s) ofassociated operations, such as backup, archive, snapshot, auxiliarycopy, or the like. Furthermore, retention parameters can specify howlong the resulting secondary copies 116 will be kept (e.g., a number ofdays, months, years, etc.), perhaps depending on organizational needsand/or compliance criteria.

When adding a new client computing device 102, administrators canmanually configure information management policies 148 and/or othersettings, e.g., via user interface 158. However, this can be an involvedprocess resulting in delays, and it may be desirable to begin dataprotection operations quickly, without awaiting human intervention.Thus, in some embodiments, system 100 automatically applies a defaultconfiguration to client computing device 102. As one example, when oneor more data agent(s) 142 are installed on a client computing device102, the installation script may register the client computing device102 with storage manager 140, which in turn applies the defaultconfiguration to the new client computing device 102. In this manner,data protection operations can begin substantially immediately. Thedefault configuration can include a default storage policy, for example,and can specify any appropriate information sufficient to begin dataprotection operations. This can include a type of data protectionoperation, scheduling information, a target secondary storage device108, data path information (e.g., a particular media agent 144), and thelike.

Another type of information management policy 148 is a “schedulingpolicy,” which specifies when and how often to perform operations.Scheduling parameters may specify with what frequency (e.g., hourly,weekly, daily, event-based, etc.) or under what triggering conditionssecondary copy or other information management operations are to takeplace. Scheduling policies in some cases are associated with particularcomponents, such as a subclient, client computing device 102, and thelike.

Another type of information management policy 148 is an “audit policy”(or “security policy”), which comprises preferences, rules and/orcriteria that protect sensitive data in system 100. For example, anaudit policy may define “sensitive objects” which are files or dataobjects that contain particular keywords (e.g., “confidential,” or“privileged”) and/or are associated with particular keywords (e.g., inmetadata) or particular flags (e.g., in metadata identifying a documentor email as personal, confidential, etc.). An audit policy may furtherspecify rules for handling sensitive objects. As an example, an auditpolicy may require that a reviewer approve the transfer of any sensitiveobjects to a cloud storage site, and that if approval is denied for aparticular sensitive object, the sensitive object should be transferredto a local primary storage device 104 instead. To facilitate thisapproval, the audit policy may further specify how a secondary storagecomputing device 106 or other system component should notify a reviewerthat a sensitive object is slated for transfer.

Another type of information management policy 148 is a “provisioningpolicy,” which can include preferences, priorities, rules, and/orcriteria that specify how client computing devices 102 (or groupsthereof) may utilize system resources, such as available storage oncloud storage and/or network bandwidth. A provisioning policy specifies,for example, data quotas for particular client computing devices 102(e.g., a number of gigabytes that can be stored monthly, quarterly orannually). Storage manager 140 or other components may enforce theprovisioning policy. For instance, media agents 144 may enforce thepolicy when transferring data to secondary storage devices 108. If aclient computing device 102 exceeds a quota, a budget for the clientcomputing device 102 (or associated department) may be adjustedaccordingly or an alert may trigger.

While the above types of information management policies 148 aredescribed as separate policies, one or more of these can be generallycombined into a single information management policy 148. For instance,a storage policy may also include or otherwise be associated with one ormore scheduling, audit, or provisioning policies or operationalparameters thereof. Moreover, while storage policies are typicallyassociated with moving and storing data, other policies may beassociated with other types of information management operations. Thefollowing is a non-exhaustive list of items that information managementpolicies 148 may specify:

-   -   schedules or other timing information, e.g., specifying when        and/or how often to perform information management operations;    -   the type of secondary copy 116 and/or copy format (e.g.,        snapshot, backup, archive, HSM, etc.);    -   a location or a class or quality of storage for storing        secondary copies 116 (e.g., one or more particular secondary        storage devices 108);    -   preferences regarding whether and how to encrypt, compress,        deduplicate, or otherwise modify or transform secondary copies        116;    -   which system components and/or network pathways (e.g., preferred        media agents 144) should be used to perform secondary storage        operations;    -   resource allocation among different computing devices or other        system components used in performing information management        operations (e.g., bandwidth allocation, available storage        capacity, etc.);    -   whether and how to synchronize or otherwise distribute files or        other data objects across multiple computing devices or hosted        services; and    -   retention information specifying the length of time primary data        112 and/or secondary copies 116 should be retained, e.g., in a        particular class or tier of storage devices, or within the        system 100.

Information management policies 148 can additionally specify or dependon historical or current criteria that may be used to determine whichrules to apply to a particular data object, system component, orinformation management operation, such as:

-   -   frequency with which primary data 112 or a secondary copy 116 of        a data object or metadata has been or is predicted to be used,        accessed, or modified;    -   time-related factors (e.g., aging information such as time since        the creation or modification of a data object);    -   deduplication information (e.g., hashes, data blocks,        deduplication block size, deduplication efficiency or other        metrics);    -   an estimated or historic usage or cost associated with different        components (e.g., with secondary storage devices 108);    -   the identity of users, applications 110, client computing        devices 102 and/or other computing devices that created,        accessed, modified, or otherwise utilized primary data 112 or        secondary copies 116;    -   a relative sensitivity (e.g., confidentiality, importance) of a        data object, e.g., as determined by its content and/or metadata;    -   the current or historical storage capacity of various storage        devices;    -   the current or historical network capacity of network pathways        connecting various components within the storage operation cell;    -   access control lists or other security information; and    -   the content of a particular data object (e.g., its textual        content) or of metadata associated with the data object.

Exemplary Storage Policy and Secondary Copy Operations

FIG. 1E includes a data flow diagram depicting performance of secondarycopy operations by an embodiment of information management system 100,according to an exemplary storage policy 148A. System 100 includes astorage manager 140, a client computing device 102 having a file systemdata agent 142A and an email data agent 142B operating thereon, aprimary storage device 104, two media agents 144A, 144B, and twosecondary storage devices 108: a disk library 108A and a tape library108B. As shown, primary storage device 104 includes primary data 112A,which is associated with a logical grouping of data associated with afile system (“file system subclient”), and primary data 1128, which is alogical grouping of data associated with email (“email subclient”). Thetechniques described with respect to FIG. 1E can be utilized inconjunction with data that is otherwise organized as well.

As indicated by the dashed box, the second media agent 144B and tapelibrary 1088 are “off-site,” and may be remotely located from the othercomponents in system 100 (e.g., in a different city, office building,etc.). Indeed, “off-site” may refer to a magnetic tape located in remotestorage, which must be manually retrieved and loaded into a tape driveto be read. In this manner, information stored on the tape library 108Bmay provide protection in the event of a disaster or other failure atthe main site(s) where data is stored.

The file system subclient 112A in certain embodiments generallycomprises information generated by the file system and/or operatingsystem of client computing device 102, and can include, for example,file system data (e.g., regular files, file tables, mount points, etc.),operating system data (e.g., registries, event logs, etc.), and thelike. The e-mail subclient 112B can include data generated by an e-mailapplication operating on client computing device 102, e.g., mailboxinformation, folder information, emails, attachments, associateddatabase information, and the like. As described above, the subclientscan be logical containers, and the data included in the correspondingprimary data 112A and 112B may or may not be stored contiguously.

The exemplary storage policy 148A includes backup copy preferences orrule set 160, disaster recovery copy preferences or rule set 162, andcompliance copy preferences or rule set 164. Backup copy rule set 160specifies that it is associated with file system subclient 166 and emailsubclient 168. Each of subclients 166 and 168 are associated with theparticular client computing device 102. Backup copy rule set 160 furtherspecifies that the backup operation will be written to disk library 108Aand designates a particular media agent 144A to convey the data to disklibrary 108A. Finally, backup copy rule set 160 specifies that backupcopies created according to rule set 160 are scheduled to be generatedhourly and are to be retained for 30 days. In some other embodiments,scheduling information is not included in storage policy 148A and isinstead specified by a separate scheduling policy.

Disaster recovery copy rule set 162 is associated with the same twosubclients 166 and 168. However, disaster recovery copy rule set 162 isassociated with tape library 108B, unlike backup copy rule set 160.Moreover, disaster recovery copy rule set 162 specifies that a differentmedia agent, namely 144B, will convey data to tape library 108B.Disaster recovery copies created according to rule set 162 will beretained for 60 days and will be generated daily. Disaster recoverycopies generated according to disaster recovery copy rule set 162 canprovide protection in the event of a disaster or other catastrophic dataloss that would affect the backup copy 116A maintained on disk library108A.

Compliance copy rule set 164 is only associated with the email subclient168, and not the file system subclient 166. Compliance copies generatedaccording to compliance copy rule set 164 will therefore not includeprimary data 112A from the file system subclient 166. For instance, theorganization may be under an obligation to store and maintain copies ofemail data for a particular period of time (e.g., 10 years) to complywith state or federal regulations, while similar regulations do notapply to file system data. Compliance copy rule set 164 is associatedwith the same tape library 108B and media agent 144B as disasterrecovery copy rule set 162, although a different storage device or mediaagent could be used in other embodiments. Finally, compliance copy ruleset 164 specifies that the copies it governs will be generated quarterlyand retained for 10 years.

Secondary Copy Jobs

A logical grouping of secondary copy operations governed by a rule setand being initiated at a point in time may be referred to as a“secondary copy job” (and sometimes may be called a “backup job,” eventhough it is not necessarily limited to creating only backup copies).Secondary copy jobs may be initiated on demand as well. Steps 1-9 belowillustrate three secondary copy jobs based on storage policy 148A.

Referring to FIG. 1E, at step 1, storage manager 140 initiates a backupjob according to the backup copy rule set 160, which logically comprisesall the secondary copy operations necessary to effectuate rules 160 instorage policy 148A every hour, including steps 1-4 occurring hourly.For instance, a scheduling service running on storage manager 140accesses backup copy rule set 160 or a separate scheduling policyassociated with client computing device 102 and initiates a backup jobon an hourly basis. Thus, at the scheduled time, storage manager 140sends instructions to client computing device 102 (i.e., to both dataagent 142A and data agent 142B) to begin the backup job.

At step 2, file system data agent 142A and email data agent 142B onclient computing device 102 respond to instructions from storage manager140 by accessing and processing the respective subclient primary data112A and 112B involved in the backup copy operation, which can be foundin primary storage device 104. Because the secondary copy operation is abackup copy operation, the data agent(s) 142A, 142B may format the datainto a backup format or otherwise process the data suitable for a backupcopy.

At step 3, client computing device 102 communicates the processed filesystem data (e.g., using file system data agent 142A) and the processedemail data (e.g., using email data agent 142B) to the first media agent144A according to backup copy rule set 160, as directed by storagemanager 140. Storage manager 140 may further keep a record in managementdatabase 146 of the association between media agent 144A and one or moreof: client computing device 102, file system subclient 112A, file systemdata agent 142A, email subclient 1128, email data agent 142B, and/orbackup copy 116A.

The target media agent 144A receives the data-agent-processed data fromclient computing device 102, and at step 4 generates and conveys backupcopy 116A to disk library 108A to be stored as backup copy 116A, againat the direction of storage manager 140 and according to backup copyrule set 160. Media agent 144A can also update its index 153 to includedata and/or metadata related to backup copy 116A, such as informationindicating where the backup copy 116A resides on disk library 108A,where the email copy resides, where the file system copy resides, dataand metadata for cache retrieval, etc. Storage manager 140 may similarlyupdate its index 150 to include information relating to the secondarycopy operation, such as information relating to the type of operation, aphysical location associated with one or more copies created by theoperation, the time the operation was performed, status informationrelating to the operation, the components involved in the operation, andthe like. In some cases, storage manager 140 may update its index 150 toinclude some or all of the information stored in index 153 of mediaagent 144A. At this point, the backup job may be considered complete.After the 30-day retention period expires, storage manager 140 instructsmedia agent 144A to delete backup copy 116A from disk library 108A andindexes 150 and/or 153 are updated accordingly.

At step 5, storage manager 140 initiates another backup job for adisaster recovery copy according to the disaster recovery rule set 162.Illustratively this includes steps 5-7 occurring daily for creatingdisaster recovery copy 1168. Illustratively, and by way of illustratingthe scalable aspects and off-loading principles embedded in system 100,disaster recovery copy 1168 is based on backup copy 116A and not onprimary data 112A and 1128.

At step 6, illustratively based on instructions received from storagemanager 140 at step 5, the specified media agent 1448 retrieves the mostrecent backup copy 116A from disk library 108A.

At step 7, again at the direction of storage manager 140 and asspecified in disaster recovery copy rule set 162, media agent 144B usesthe retrieved data to create a disaster recovery copy 1168 and store itto tape library 1088. In some cases, disaster recovery copy 1168 is adirect, mirror copy of backup copy 116A, and remains in the backupformat. In other embodiments, disaster recovery copy 1168 may be furthercompressed or encrypted, or may be generated in some other manner, suchas by using primary data 112A and 1128 from primary storage device 104as sources. The disaster recovery copy operation is initiated once a dayand disaster recovery copies 1168 are deleted after 60 days; indexes 153and/or 150 are updated accordingly when/after each informationmanagement operation is executed and/or completed. The present backupjob may be considered completed.

At step 8, storage manager 140 initiates another backup job according tocompliance rule set 164, which performs steps 8-9 quarterly to createcompliance copy 116C. For instance, storage manager 140 instructs mediaagent 144B to create compliance copy 116C on tape library 1088, asspecified in the compliance copy rule set 164.

At step 9 in the example, compliance copy 116C is generated usingdisaster recovery copy 1168 as the source. This is efficient, becausedisaster recovery copy resides on the same secondary storage device andthus no network resources are required to move the data. In otherembodiments, compliance copy 116C is instead generated using primarydata 1128 corresponding to the email subclient or using backup copy 116Afrom disk library 108A as source data. As specified in the illustratedexample, compliance copies 116C are created quarterly, and are deletedafter ten years, and indexes 153 and/or 150 are kept up-to-dateaccordingly.

Exemplary Applications of Storage Policies—Information GovernancePolicies and Classification

Again referring to FIG. 1E, storage manager 140 may permit a user tospecify aspects of storage policy 148A. For example, the storage policycan be modified to include information governance policies to define howdata should be managed in order to comply with a certain regulation orbusiness objective. The various policies may be stored, for example, inmanagement database 146. An information governance policy may align withone or more compliance tasks that are imposed by regulations or businessrequirements. Examples of information governance policies might includea Sarbanes-Oxley policy, a HIPAA policy, an electronic discovery(e-discovery) policy, and so on.

Information governance policies allow administrators to obtain differentperspectives on an organization's online and offline data, without theneed for a dedicated data silo created solely for each differentviewpoint. As described previously, the data storage systems hereinbuild an index that reflects the contents of a distributed data set thatspans numerous clients and storage devices, including both primary dataand secondary copies, and online and offline copies. An organization mayapply multiple information governance policies in a top-down manner overthat unified data set and indexing schema in order to view andmanipulate the data set through different lenses, each of which isadapted to a particular compliance or business goal. Thus, for example,by applying an e-discovery policy and a Sarbanes-Oxley policy, twodifferent groups of users in an organization can conduct two verydifferent analyses of the same underlying physical set of data/copies,which may be distributed throughout the information management system.

An information governance policy may comprise a classification policy,which defines a taxonomy of classification terms or tags relevant to acompliance task and/or business objective. A classification policy mayalso associate a defined tag with a classification rule. Aclassification rule defines a particular combination of criteria, suchas users who have created, accessed or modified a document or dataobject; file or application types; content or metadata keywords; clientsor storage locations; dates of data creation and/or access; reviewstatus or other status within a workflow (e.g., reviewed orun-reviewed); modification times or types of modifications; and/or anyother data attributes in any combination, without limitation. Aclassification rule may also be defined using other classification tagsin the taxonomy. The various criteria used to define a classificationrule may be combined in any suitable fashion, for example, via Booleanoperators, to define a complex classification rule. As an example, ane-discovery classification policy might define a classification tag“privileged” that is associated with documents or data objects that (1)were created or modified by legal department staff, or (2) were sent toor received from outside counsel via email, or (3) contain one of thefollowing keywords: “privileged” or “attorney” or “counsel,” or otherlike terms. Accordingly, all these documents or data objects will beclassified as “privileged.”

One specific type of classification tag, which may be added to an indexat the time of indexing, is an “entity tag.” An entity tag may be, forexample, any content that matches a defined data mask format. Examplesof entity tags might include, e.g., social security numbers (e.g., anynumerical content matching the formatting mask XXX-XX-XXXX), credit cardnumbers (e.g., content having a 13-16 digit string of numbers), SKUnumbers, product numbers, etc. A user may define a classification policyby indicating criteria, parameters or descriptors of the policy via agraphical user interface, such as a form or page with fields to befilled in, pull-down menus or entries allowing one or more of severaloptions to be selected, buttons, sliders, hypertext links or other knownuser interface tools for receiving user input, etc. For example, a usermay define certain entity tags, such as a particular product number orproject ID. In some implementations, the classification policy can beimplemented using cloud-based techniques. For example, the storagedevices may be cloud storage devices, and the storage manager 140 mayexecute cloud service provider API over a network to classify datastored on cloud storage devices.

Restore Operations from Secondary Copies

While not shown in FIG. 1E, at some later point in time, a restoreoperation can be initiated involving one or more of secondary copies116A, 1168, and 116C. A restore operation logically takes a selectedsecondary copy 116, reverses the effects of the secondary copy operationthat created it, and stores the restored data to primary storage where aclient computing device 102 may properly access it as primary data. Amedia agent 144 and an appropriate data agent 142 (e.g., executing onthe client computing device 102) perform the tasks needed to complete arestore operation. For example, data that was encrypted, compressed,and/or deduplicated in the creation of secondary copy 116 will becorrespondingly rehydrated (reversing deduplication), uncompressed, andunencrypted into a format appropriate to primary data. Metadata storedwithin or associated with the secondary copy 116 may be used during therestore operation. In general, restored data should be indistinguishablefrom other primary data 112. Preferably, the restored data has fullyregained the native format that may make it immediately usable byapplication 110.

As one example, a user may manually initiate a restore of backup copy116A, e.g., by interacting with user interface 158 of storage manager140 or with a web-based console with access to system 100. Storagemanager 140 may accesses data in its index 150 and/or managementdatabase 146 (and/or the respective storage policy 148A) associated withthe selected backup copy 116A to identify the appropriate media agent144A and/or secondary storage device 108A where the secondary copyresides. The user may be presented with a representation (e.g., stub,thumbnail, listing, etc.) and metadata about the selected secondarycopy, in order to determine whether this is the appropriate copy to berestored, e.g., date that the original primary data was created. Storagemanager 140 will then instruct media agent 144A and an appropriate dataagent 142 on the target client computing device 102 to restore secondarycopy 116A to primary storage device 104. A media agent may be selectedfor use in the restore operation based on a load balancing algorithm, anavailability based algorithm, or other criteria. The selected mediaagent, e.g., 144A, retrieves secondary copy 116A from disk library 108A.For instance, media agent 144A may access its index 153 to identify alocation of backup copy 116A on disk library 108A, or may accesslocation information residing on disk library 108A itself.

In some cases a backup copy 116A that was recently created or accessed,may be cached to speed up the restore operation. In such a case, mediaagent 144A accesses a cached version of backup copy 116A residing inindex 153, without having to access disk library 108A for some or all ofthe data. Once it has retrieved backup copy 116A, the media agent 144Acommunicates the data to the requesting client computing device 102.Upon receipt, file system data agent 142A and email data agent 142B mayunpack (e.g., restore from a backup format to the native applicationformat) the data in backup copy 116A and restore the unpackaged data toprimary storage device 104. In general, secondary copies 116 may berestored to the same volume or folder in primary storage device 104 fromwhich the secondary copy was derived; to another storage location orclient computing device 102; to shared storage, etc. In some cases, thedata may be restored so that it may be used by an application 110 of adifferent version/vintage from the application that created the originalprimary data 112.

Exemplary Secondary Copy Formatting

The formatting and structure of secondary copies 116 can vary dependingon the embodiment. In some cases, secondary copies 116 are formatted asa series of logical data units or “chunks” (e.g., 512 MB, 1 GB, 2 GB, 4GB, or 8 GB chunks). This can facilitate efficient communication andwriting to secondary storage devices 108, e.g., according to resourceavailability. For example, a single secondary copy 116 may be written ona chunk-by-chunk basis to one or more secondary storage devices 108. Insome cases, users can select different chunk sizes, e.g., to improvethroughput to tape storage devices. Generally, each chunk can include aheader and a payload. The payload can include files (or other dataunits) or subsets thereof included in the chunk, whereas the chunkheader generally includes metadata relating to the chunk, some or all ofwhich may be derived from the payload. For example, during a secondarycopy operation, media agent 144, storage manager 140, or other componentmay divide files into chunks and generate headers for each chunk byprocessing the files. Headers can include a variety of information suchas file and/or volume identifier(s), offset(s), and/or other informationassociated with the payload data items, a chunk sequence number, etc.Importantly, in addition to being stored with secondary copy 116 onsecondary storage device 108, chunk headers can also be stored to index153 of the associated media agent(s) 144 and/or to index 150 associatedwith storage manager 140. This can be useful for providing fasterprocessing of secondary copies 116 during browsing, restores, or otheroperations. In some cases, once a chunk is successfully transferred to asecondary storage device 108, the secondary storage device 108 returnsan indication of receipt, e.g., to media agent 144 and/or storagemanager 140, which may update their respective indexes 153, 150accordingly. During restore, chunks may be processed (e.g., by mediaagent 144) according to the information in the chunk header toreassemble the files.

Data can also be communicated within system 100 in data channels thatconnect client computing devices 102 to secondary storage devices 108.These data channels can be referred to as “data streams,” and multipledata streams can be employed to parallelize an information managementoperation, improving data transfer rate, among other advantages. Exampledata formatting techniques including techniques involving datastreaming, chunking, and the use of other data structures in creatingsecondary copies are described in U.S. Pat. Nos. 7,315,923, 8,156,086,and 8,578,120.

FIGS. 1F and 1G are diagrams of example data streams 170 and 171,respectively, which may be employed for performing informationmanagement operations. Referring to FIG. 1F, data agent 142 forms datastream 170 from source data associated with a client computing device102 (e.g., primary data 112). Data stream 170 is composed of multiplepairs of stream header 172 and stream data (or stream payload) 174. Datastreams 170 and 171 shown in the illustrated example are for asingle-instanced storage operation, and a stream payload 174 thereforemay include both single-instance (SI) data and/or non-SI data. A streamheader 172 includes metadata about the stream payload 174. This metadatamay include, for example, a length of the stream payload 174, anindication of whether the stream payload 174 is encrypted, an indicationof whether the stream payload 174 is compressed, an archive fileidentifier (ID), an indication of whether the stream payload 174 issingle instanceable, and an indication of whether the stream payload 174is a start of a block of data.

Referring to FIG. 1G, data stream 171 has the stream header 172 andstream payload 174 aligned into multiple data blocks. In this example,the data blocks are of size 64 KB. The first two stream header 172 andstream payload 174 pairs comprise a first data block of size 64 KB. Thefirst stream header 172 indicates that the length of the succeedingstream payload 174 is 63 KB and that it is the start of a data block.The next stream header 172 indicates that the succeeding stream payload174 has a length of 1 KB and that it is not the start of a new datablock. Immediately following stream payload 174 is a pair comprising anidentifier header 176 and identifier data 178. The identifier header 176includes an indication that the succeeding identifier data 178 includesthe identifier for the immediately previous data block. The identifierdata 178 includes the identifier that the data agent 142 generated forthe data block. The data stream 171 also includes other stream header172 and stream payload 174 pairs, which may be for SI data and/or non-SIdata.

FIG. 1H is a diagram illustrating data structures 180 that may be usedto store blocks of SI data and non-SI data on a storage device (e.g.,secondary storage device 108). According to certain embodiments, datastructures 180 do not form part of a native file system of the storagedevice. Data structures 180 include one or more volume folders 182, oneor more chunk folders 184/185 within the volume folder 182, and multiplefiles within chunk folder 184. Each chunk folder 184/185 includes ametadata file 186/187, a metadata index file 188/189, one or morecontainer files 190/191/193, and a container index file 192/194.Metadata file 186/187 stores non-SI data blocks as well as links to SIdata blocks stored in container files. Metadata index file 188/189stores an index to the data in the metadata file 186/187. Containerfiles 190/191/193 store SI data blocks. Container index file 192/194stores an index to container files 190/191/193. Among other things,container index file 192/194 stores an indication of whether acorresponding block in a container file 190/191/193 is referred to by alink in a metadata file 186/187. For example, data block B2 in thecontainer file 190 is referred to by a link in metadata file 187 inchunk folder 185. Accordingly, the corresponding index entry incontainer index file 192 indicates that data block B2 in container file190 is referred to. As another example, data block B1 in container file191 is referred to by a link in metadata file 187, and so thecorresponding index entry in container index file 192 indicates thatthis data block is referred to.

As an example, data structures 180 illustrated in FIG. 1H may have beencreated as a result of separate secondary copy operations involving twoclient computing devices 102. For example, a first secondary copyoperation on a first client computing device 102 could result in thecreation of the first chunk folder 184, and a second secondary copyoperation on a second client computing device 102 could result in thecreation of the second chunk folder 185. Container files 190/191 in thefirst chunk folder 184 would contain the blocks of SI data of the firstclient computing device 102. If the two client computing devices 102have substantially similar data, the second secondary copy operation onthe data of the second client computing device 102 would result in mediaagent 144 storing primarily links to the data blocks of the first clientcomputing device 102 that are already stored in the container files190/191. Accordingly, while a first secondary copy operation may resultin storing nearly all of the data subject to the operation, subsequentsecondary storage operations involving similar data may result insubstantial data storage space savings, because links to already storeddata blocks can be stored instead of additional instances of datablocks.

If the operating system of the secondary storage computing device 106 onwhich media agent 144 operates supports sparse files, then when mediaagent 144 creates container files 190/191/193, it can create them assparse files. A sparse file is a type of file that may include emptyspace (e.g., a sparse file may have real data within it, such as at thebeginning of the file and/or at the end of the file, but may also haveempty space in it that is not storing actual data, such as a contiguousrange of bytes all having a value of zero). Having container files190/191/193 be sparse files allows media agent 144 to free up space incontainer files 190/191/193 when blocks of data in container files190/191/193 no longer need to be stored on the storage devices. In someexamples, media agent 144 creates a new container file 190/191/193 whena container file 190/191/193 either includes 100 blocks of data or whenthe size of the container file 190 exceeds 50 MB. In other examples,media agent 144 creates a new container file 190/191/193 when acontainer file 190/191/193 satisfies other criteria (e.g., it containsfrom approx. 100 to approx. 1000 blocks or when its size exceedsapproximately 50 MB to 1 GB). In some cases, a file on which a secondarycopy operation is performed may comprise a large number of data blocks.For example, a 100 MB file may comprise 400 data blocks of size 256 KB.If such a file is to be stored, its data blocks may span more than onecontainer file, or even more than one chunk folder. As another example,a database file of 20 GB may comprise over 40,000 data blocks of size512 KB. If such a database file is to be stored, its data blocks willlikely span multiple container files, multiple chunk folders, andpotentially multiple volume folders. Restoring such files may requireaccessing multiple container files, chunk folders, and/or volume foldersto obtain the requisite data blocks.

Using Backup Data for Replication and Disaster Recovery (“LiveSynchronization”)

There is an increased demand to off-load resource intensive informationmanagement tasks (e.g., data replication tasks) away from productiondevices (e.g., physical or virtual client computing devices) in order tomaximize production efficiency. At the same time, enterprises expectaccess to readily-available up-to-date recovery copies in the event offailure, with little or no production downtime.

FIG. 2A illustrates a system 200 configured to address these and otherissues by using backup or other secondary copy data to synchronize asource subsystem 201 (e.g., a production site) with a destinationsubsystem 203 (e.g., a failover site). Such a technique can be referredto as “live synchronization” and/or “live synchronization replication.”In the illustrated embodiment, the source client computing devices 202 ainclude one or more virtual machines (or “VMs”) executing on one or morecorresponding VM host computers 205 a, though the source need not bevirtualized. The destination site 203 may be at a location that isremote from the production site 201, or may be located in the same datacenter, without limitation. One or more of the production site 201 anddestination site 203 may reside at data centers at known geographiclocations, or alternatively may operate “in the cloud.”

The synchronization can be achieved by generally applying an ongoingstream of incremental backups from the source subsystem 201 to thedestination subsystem 203, such as according to what can be referred toas an “incremental forever” approach. FIG. 2A illustrates an embodimentof a data flow which may be orchestrated at the direction of one or morestorage managers (not shown). At step 1, the source data agent(s) 242 aand source media agent(s) 244 a work together to write backup or othersecondary copies of the primary data generated by the source clientcomputing devices 202 a into the source secondary storage device(s) 208a. At step 2, the backup/secondary copies are retrieved by the sourcemedia agent(s) 244 a from secondary storage. At step 3, source mediaagent(s) 244 a communicate the backup/secondary copies across a networkto the destination media agent(s) 244 b in destination subsystem 203.

As shown, the data can be copied from source to destination in anincremental fashion, such that only changed blocks are transmitted, andin some cases multiple incremental backups are consolidated at thesource so that only the most current changed blocks are transmitted toand applied at the destination. An example of live synchronization ofvirtual machines using the “incremental forever” approach is found inU.S. Patent Application No. 62/265,339 entitled “Live Synchronizationand Management of Virtual Machines across Computing and VirtualizationPlatforms and Using Live Synchronization to Support Disaster Recovery.”Moreover, a deduplicated copy can be employed to further reduce networktraffic from source to destination. For instance, the system can utilizethe deduplicated copy techniques described in U.S. Pat. No. 9,239,687,entitled “Systems and Methods for Retaining and Using Data BlockSignatures in Data Protection Operations.”

At step 4, destination media agent(s) 244 b write the receivedbackup/secondary copy data to the destination secondary storagedevice(s) 208 b. At step 5, the synchronization is completed when thedestination media agent(s) and destination data agent(s) 242 b restorethe backup/secondary copy data to the destination client computingdevice(s) 202 b. The destination client computing device(s) 202 b may bekept “warm” awaiting activation in case failure is detected at thesource. This synchronization/replication process can incorporate thetechniques described in U.S. patent application Ser. No. 14/721,971,entitled “Replication Using Deduplicated Secondary Copy Data.”

Where the incremental backups are applied on a frequent, on-going basis,the synchronized copies can be viewed as mirror or replication copies.Moreover, by applying the incremental backups to the destination site203 using backup or other secondary copy data, the production site 201is not burdened with the synchronization operations. Because thedestination site 203 can be maintained in a synchronized “warm” state,the downtime for switching over from the production site 201 to thedestination site 203 is substantially less than with a typical restorefrom secondary storage. Thus, the production site 201 may flexibly andefficiently fail over, with minimal downtime and with relativelyup-to-date data, to a destination site 203, such as a cloud-basedfailover site. The destination site 203 can later be reversesynchronized back to the production site 201, such as after repairs havebeen implemented or after the failure has passed.

Integrating with the Cloud Using File System Protocols

Given the ubiquity of cloud computing, it can be increasingly useful toprovide data protection and other information management services in ascalable, transparent, and highly plug-able fashion. FIG. 2B illustratesan information management system 200 having an architecture thatprovides such advantages, and incorporates use of a standard file systemprotocol between primary and secondary storage subsystems 217, 218. Asshown, the use of the network file system (NFS) protocol (or any anotherappropriate file system protocol such as that of the Common InternetFile System (CIFS)) allows data agent 242 to be moved from the primarystorage subsystem 217 to the secondary storage subsystem 218. Forinstance, as indicated by the dashed box 206 around data agent 242 andmedia agent 244, data agent 242 can co-reside with media agent 244 onthe same server (e.g., a secondary storage computing device such ascomponent 106), or in some other location in secondary storage subsystem218.

Where NFS is used, for example, secondary storage subsystem 218allocates an NFS network path to the client computing device 202 or toone or more target applications 210 running on client computing device202. During a backup or other secondary copy operation, the clientcomputing device 202 mounts the designated NFS path and writes data tothat NFS path. The NFS path may be obtained from NFS path data 215stored locally at the client computing device 202, and which may be acopy of or otherwise derived from NFS path data 219 stored in thesecondary storage subsystem 218.

Write requests issued by client computing device(s) 202 are received bydata agent 242 in secondary storage subsystem 218, which translates therequests and works in conjunction with media agent 244 to process andwrite data to a secondary storage device(s) 208, thereby creating abackup or other secondary copy. Storage manager 240 can include apseudo-client manager 217, which coordinates the process by, among otherthings, communicating information relating to client computing device202 and application 210 (e.g., application type, client computing deviceidentifier, etc.) to data agent 242, obtaining appropriate NFS path datafrom the data agent 242 (e.g., NFS path information), and deliveringsuch data to client computing device 202.

Conversely, during a restore or recovery operation client computingdevice 202 reads from the designated NFS network path, and the readrequest is translated by data agent 242. The data agent 242 then workswith media agent 244 to retrieve, re-process (e.g., re-hydrate,decompress, decrypt), and forward the requested data to client computingdevice 202 using NFS.

By moving specialized software associated with system 200 such as dataagent 242 off the client computing devices 202, the illustrativearchitecture effectively decouples the client computing devices 202 fromthe installed components of system 200, improving both scalability andplug-ability of system 200. Indeed, the secondary storage subsystem 218in such environments can be treated simply as a read/write NFS targetfor primary storage subsystem 217, without the need for informationmanagement software to be installed on client computing devices 202. Asone example, an enterprise implementing a cloud production computingenvironment can add VM client computing devices 202 without installingand configuring specialized information management software on theseVMs. Rather, backups and restores are achieved transparently, where thenew VMs simply write to and read from the designated NFS path. Anexample of integrating with the cloud using file system protocols orso-called “infinite backup” using NFS share is found in U.S. PatentApplication No. 62/294,920, entitled “Data Protection Operations Basedon Network Path Information.” Examples of improved data restorationscenarios based on network-path information, including using storedbackups effectively as primary data sources, may be found in U.S. PatentApplication No. 62/297,057, entitled “Data Restoration Operations Basedon Network Path Information.”

Highly Scalable Managed Data Pool Architecture

Enterprises are seeing explosive data growth in recent years, often fromvarious applications running in geographically distributed locations.FIG. 2C shows a block diagram of an example of a highly scalable,managed data pool architecture useful in accommodating such data growth.The illustrated system 200, which may be referred to as a “web-scale”architecture according to certain embodiments, can be readilyincorporated into both open compute/storage and common-cloudarchitectures.

The illustrated system 200 includes a grid 245 of media agents 244logically organized into a control tier 231 and a secondary or storagetier 233. Media agents assigned to the storage tier 233 can beconfigured to manage a secondary storage pool 208 as a deduplicationstore, and be configured to receive client write and read requests fromthe primary storage subsystem 217, and direct those requests to thesecondary tier 233 for servicing. For instance, media agents CMA1-CMA3in the control tier 231 maintain and consult one or more deduplicationdatabases 247, which can include deduplication information (e.g., datablock hashes, data block links, file containers for deduplicated files,etc.) sufficient to read deduplicated files from secondary storage pool208 and write deduplicated files to secondary storage pool 208. Forinstance, system 200 can incorporate any of the deduplication systemsand methods shown and described in U.S. Pat. No. 9,020,900, entitled“Distributed Deduplicated Storage System,” and U.S. Pat. Pub. No.2014/0201170, entitled “High Availability Distributed DeduplicatedStorage System.”

Media agents SMA1-SMA6 assigned to the secondary tier 233 receive writeand read requests from media agents CMA1-CMA3 in control tier 231, andaccess secondary storage pool 208 to service those requests. Mediaagents CMA1-CMA3 in control tier 231 can also communicate with secondarystorage pool 208, and may execute read and write requests themselves(e.g., in response to requests from other control media agentsCMA1-CMA3) in addition to issuing requests to media agents in secondarytier 233. Moreover, while shown as separate from the secondary storagepool 208, deduplication database(s) 247 can in some cases reside instorage devices in secondary storage pool 208.

As shown, each of the media agents 244 (e.g., CMA1-CMA3, SMA1-SMA6,etc.) in grid 245 can be allocated a corresponding dedicated partition251A-2511, respectively, in secondary storage pool 208. Each partition251 can include a first portion 253 containing data associated with(e.g., stored by) media agent 244 corresponding to the respectivepartition 251. System 200 can also implement a desired level ofreplication, thereby providing redundancy in the event of a failure of amedia agent 244 in grid 245. Along these lines, each partition 251 canfurther include a second portion 255 storing one or more replicationcopies of the data associated with one or more other media agents 244 inthe grid.

System 200 can also be configured to allow for seamless addition ofmedia agents 244 to grid 245 via automatic configuration. As oneillustrative example, a storage manager (not shown) or other appropriatecomponent may determine that it is appropriate to add an additional nodeto control tier 231, and perform some or all of the following: (i)assess the capabilities of a newly added or otherwise availablecomputing device as satisfying a minimum criteria to be configured as orhosting a media agent in control tier 231; (ii) confirm that asufficient amount of the appropriate type of storage exists to supportan additional node in control tier 231 (e.g., enough disk drive capacityexists in storage pool 208 to support an additional deduplicationdatabase 247); (iii) install appropriate media agent software on thecomputing device and configure the computing device according to apre-determined template; (iv) establish a partition 251 in the storagepool 208 dedicated to the newly established media agent 244; and (v)build any appropriate data structures (e.g., an instance ofdeduplication database 247). An example of highly scalable managed datapool architecture or so-called web-scale architecture for storage anddata management is found in U.S. Patent Application No. 62/273,286entitled “Redundant and Robust Distributed Deduplication Data StorageSystem.”

The embodiments and components thereof disclosed in FIGS. 2A, 2B, and2C, as well as those in FIGS. 1A-1H, may be implemented in anycombination and permutation to satisfy data storage management andinformation management needs at one or more locations and/or datacenters.

Heartbeat Monitoring of Virtual Machines for Initiating Failover and/orFailback Operations in a Data Storage Management System

FIG. 3 is a block diagram illustrating some salient portions of a system300 for heartbeat monitoring of virtual machines for initiating failoverand/or failback operations, according to an illustrative embodiment ofthe present invention. As shown here, system 300 comprises: VM datacenter 301; VM data center 302; cloud computing resources 303; andstorage manager 340 comprising management database 346.

System 300 is also referred to herein as a “VM heartbeat monitoringsystem” at least because it comprises a plurality of heartbeat monitornodes that monitor respective one or more target virtual machines (VMs).Because system 300 is also a data storage management system, certaincomponents are configured to handle failover and failback operations forfailed target VMs.

VM data center 301 represents a data center comprising a productioncomputing environment including virtual machines (VMs) to be describedin more detail in another figure. Because the production data center canfail over to another data center, data center 301 is referred to hereinas a source relative to a failover to data center 302, which is referredto as a destination. In a failback scenario, the original destinationbecomes the failback source and the original source is the failbackdestination. VM data center 301 is generally distinguished herein from acloud-based environment such as 303, by being based in and directlymanaged by the enterprise that also owns/operates the illustrative datastorage management system 300, such as a data center in a corporateinformation technology department.

VM data center 302 represents a data center comprising a computingenvironment including replicated virtual machines (VMs) to be describedin more detail in another figure. VM data center 302 is the failbackdestination relative to VM data center 301. VM data center 302 isgenerally distinguished herein from a cloud-based environment such as303, by being based in and directly managed by the enterprise that alsoowns/operates the illustrative data storage management system 300, suchas a data center in a corporate information technology department.

Cloud computing resources, or cloud-based data center, 303 comprisescomputing resources available from a cloud services provider, e.g.,Microsoft Azure, Amazon Web Services, etc. The invention is not limitedto these public-cloud service providers, however, because any privateand/or public cloud infrastructure can be configured as cloud computingresources 303 in system 300.

Storage manager 340 is analogous to storage manager 140 and furthercomprises additional features needed for operating within system 300.Storage manager 340 is said to manage system 300, which includesmanagement of storage operations (such as failover operations for failedVMs and/or other failed computing devices) as well as configuring theheartbeat monitor nodes, keeping track of the current master monitornode, configuring certain monitor nodes as members of a quorum, etc., asdescribed in further detail herein. For example, storage manager 340receives notifications from heartbeat monitor nodes sufficient forstorage manager 340 to call failover (or conversely, to call failback)on VMs reported failed based on the illustrative VM heartbeat monitoringnetwork. The operations involved in executing and managing VMfailovers/failbacks are available in other data storage managementsystems and are known in the art as managed by storage manager 340. Incontrast, the framework disclosed herein for VM heartbeat monitoringleading to a notice of failure to the storage manager is part of theillustrative embodiments according to the present invention.

Management database 346 is a logical sub-component of storage manager340. Management database 346 is analogous to management database 146described elsewhere herein and further comprises information used bystorage manager 340 to manage VM heartbeat monitoring in system 300. Seealso FIG. 6A.

Although the present figure depicts one source data center, onedestination data center, and one cloud-based data center, the presentinvention is not so limited, as described in further detail in otherfigures herein. Any number or combination of source, destination, and/orcloud-based data centers can be configured for VM heartbeat monitoringand failover and/or failback operations. As shown in FIGS. 13 and 14,the present invention also includes VM heartbeat monitoring forinitiating cloud-to-cloud failover and/or failback operations. Likewiseincluded are VM heartbeat monitoring for initiating data-center-to-cloudand cloud-to-data-center failover and/or failback operations.

FIG. 4 is a block diagram illustrating certain details of system 300,including a plurality of heartbeat monitor nodes 410. FIG. 4 depicts:source data center 301, comprising VM host/server 401, production VMs411, and three heartbeat monitor nodes 410; destination data center 302,comprising VM host/server 402, replica VMs 421, and one heartbeatmonitor node 410; cloud computing resources 303 comprising one heartbeatmonitor node 410; storage manager 340; and quorum 440 comprising thefive depicted monitor nodes 410.

The unidirectional arrows depict heartbeat monitoring of production VMs411 performed by three heartbeat monitor nodes 410 in source data center301, e.g., using ping monitoring logic 610. The dotted bidirectionalarrows depict a communicative coupling between each heartbeat monitornode 410 and storage manager 340, e.g., using enhanced virtual serverdata agent 542. The bold bidirectional arrows depict a quorumrelationship among the five heartbeat monitor nodes 410, which formquorum 440, e.g., using heartbeat monitoring distributed file system545, data files 712, and watch processes 900.

VM host/server 401 is a computing device comprising one or moreprocessors and suitable computer memory for hosting one or more virtualmachines (VMs), such as virtual machines 411. As is known in the art, aVM host such as 401 also comprises a hypervisor, without limitation onthe type or technology thereof. Although VM host/server 401 is depictedhere as one computing device, in alternative embodiments component 401is a collective arrangement such as a VM data center that operates as aunified grouping of VMs and comprises more than one VM host/servercomputing device. VM host/server computing devices and VM data centersare well known in the art.

VM host/server 402 is a computing device comprising one or moreprocessors and suitable computer memory for hosting one or more virtualmachines (VMs), such as virtual machines 421. As is known in the art, aVM host such as 402 also comprises a hypervisor, without limitation onthe type or technology thereof. Although VM host/server 402 is depictedhere as one computing device, in alternative embodiments component 402is a collective arrangement such as a VM data center that operates as aunified grouping of VMs and comprises more than one VM host/servercomputing device. VM host/server computing devices and VM data centersare well known in the art.

Heartbeat monitor nodes 410 are active components that form the backboneof the VM heartbeat monitoring systems disclosed herein. Each heartbeatmonitor node 410 is in communication with storage manager 340 as shownby the dotted bidirectional arrows. Each depicted heartbeat monitor node410 is designated “M” for master, “W” for worker, and/or “O” forobserver, each of which carries out a distinct role. In someembodiments, a master monitor node also carries out a worker role, andis designated “M W” to so denote its dual role. A given heartbeatmonitor node can be configured to execute on a virtual machine and canalso be configured to execute on a computing device withoutvirtualization, without limitation (see FIG. 5). Heartbeat monitor nodes410 depicted in the present figure are all part of quorum 440, but inalternative configurations a heartbeat monitor node (e.g., 1110 in FIG.11) can perform VM heartbeat monitoring operations as a worker nodewithout participating in quorum 440. In other embodiments, heartbeatmonitor nodes comprise not only the functionality of a heartbeat monitornode 410 but also firewall functionality (e.g., 1310 in FIG. 13) andeven include storage manager functionality (e.g., 1410 in FIG. 14).

Each VM 411 is a virtual machine executing in source data center 301. VM411 is referred to herein as a production VM, because its illustrativerole here is to host applications used in a “live” production dataprocessing environment, and therefore VM 411 is a component that ismanaged under the data storage management system 300, e.g., backup andfailover. Any VM technology, size, type, underlying hypervisor, size,and/or configuration is suitable for the present invention, withoutlimitation. Virtual machines are well known in the art. According to theillustrative embodiments each VM 411 is targeted by and monitored by aheartbeat monitor node 410 while the target VM is active andoperational. The process for assigning each VM 411 as a target to asuitable heartbeat monitor node is referred to herein as “VMdistribution logic” and is described in more detail elsewhere herein,e.g., FIGS. 6A and 18.

Each VM 421 is a virtual machine configured in destination data center302. VM 421 is referred to herein as a replica VM, because it undergoescontinuous replication and/or live synchronization from its counterpartproduction VM 411. Each VM 421 is pre-configured (e.g., via storagemanager 340) as a suitable replacement able to take over operations in afailover scenario when the corresponding source VM 411 fails. Thus, VM421 is pre-configured to correspond to a certain source VM 411 so thatVM 421 is suitably configured for failover. Typically, VM 421 isconfigured to be as close to its corresponding source VM 411, thoughabsolute identity is not a requirement. Configuring replica VMs (e.g.,using continuous replication and/or live sync features) forfailover/failback is well known in the art. According to theillustrative embodiments VMs 421 are not monitored by heartbeat monitornodes pre-failover, although the invention is not so limited.

Quorum 440 comprises the five depicted heartbeat monitor nodes 410.Source data center 301 comprises a master node also operating as aworker node (M W) and two worker nodes (W); one observer node (O) incloud 303; and another observer node (O) in destination data center 302.The quorum concept is well known in Apache ZooKeeper networks, but othernovel aspects are introduced herein according to the illustrativeembodiments of the present invention, e.g., what constitutes a quorumnode in the VM heartbeat monitoring system, quorum node relationshipswith storage manager 340, including when the master is established, howthe quorum operates after a failover/failback, and other aspects withoutlimitation. Likewise, the Apache ZooKeeper concepts of master, observer,and worker in a quorum are also well known, but other novel aspects areintroduced herein according to the illustrative embodiments of thepresent invention, e.g., each monitor node in communication with storagemanager 340, configuration of the distributed file system, node-to-nodecommunications protocol and data file content/format, specialconfigurations for facilitating cloud-to-cloud failover/failback, masternode selection logic, VM distribution logic, ping monitoring logic, andother aspects without limitation. See also FIGS. 5 and 6.

FIG. 5 is a block diagram illustrating heartbeat monitor nodes 410 incommunication with storage manager 340; and also in communication witheach other via heartbeat monitoring distributed file system 545. FIG. 5depicts: storage manager 340; VM host/server 401 comprising heartbeatmonitor node 410-1 represents a VM that executes enhanced virtual serverdata agent 542 comprising heartbeat monitoring distributed file system545, wherein the hosting VM is supported by hypervisor 520; andunvirtualized computing device 501 comprising heartbeat monitor node410-2 executing an enhanced virtual server data agent 542 comprisingheartbeat monitoring distributed file system 545.

Heartbeat monitor node 410-1 represents a VM supported by hypervisor 520executing on VM host/server 401. Heartbeat monitor node 410-1 istherefore referred to herein as a “virtualized monitor node.” Accordingto an illustrative embodiment, the host VM is functionally dedicated tooperate as heartbeat monitor node 410-1, though the invention is not solimited. Heartbeat monitor node 410-1 need not be hosted by the same VMhost/server or VM center as production VMs 411, although its “distance”from any given VM 411 may affect whether node 410-1 will be chosen tomonitor the given target VM 411. See e.g., VM distribution rules in FIG.18. Although heartbeat monitor node 410-1 is shown here hosted by acomponent of source data center 301, a virtualized heartbeat monitornode such as 410-1 can operate in other data centers that includevirtualized resources such as destination data center 302, cloud-basedcomputing resources 303, cloud regions 1303-1 and/or 1302-2 (FIGS. 13,14), etc., without limitation.

Heartbeat monitor node 410-2 is hosted by an unvirtualized computingdevice 501, not by a virtual machine, and therefore this heartbeatmonitor node is referred to herein as an “unvirtualized monitor node.”According to an illustrative embodiment, the hosting computing device501 is functionally dedicated to operate as a heartbeat monitor node410-2, though the invention is not so limited. Heartbeat monitor node410-2 comprises all the functional components necessary to perform VMheartbeat monitoring of any number of target VMs (e.g., 411). Anunvirtualized heartbeat node such as 410-2 can operate in any datacenter that includes unvirtualized resources, e.g., data center 301and/or 302, without limitation.

Computing device 501 comprises one or more processors and suitablecomputer memory for executing computer programs. Computing device 501lacks a hypervisor and does not host virtual machines and is thereforereferred to herein as “unvirtualized.” Computing device 501 can operatein any data center that includes unvirtualized resources, e.g., datacenter 301 and/or 302, without limitation

Hypervisor 520 executes on VM host/server 401 in a manner well known inthe art. Hypervisors are well known in the art and the present inventionis not limited to any particular hypervisor version, make, or model. VMhost/server 402 also has a hypervisor (not shown) for hosting VMs 421.Likewise, other depicted virtualized monitor nodes, e.g., in cloud-basedcomputing resources 303, in cloud region 1303-1, in cloud region 1303-2also have corresponding hypervisors for hosting the respective VM.

Enhanced virtual server data agent 542 (or “data agent 542”) isanalogous to data agent 142 configured for protecting virtual machinesand further comprises additional functionality for operating as aheartbeat monitor node in the illustrative systems herein such as system300, 1100, 1200, 1300, 1400, etc. without limitation. Data agent 542 isin communication with storage manager 340 as depicted by the dottedbidirectional arrow therebetween, including communications relating toVM heartbeat monitoring as well as pertaining to storage managementoperations, e.g., backups.

Heartbeat monitoring distributed file system 545 is part of data agent542 and is used for communicating information among heartbeat monitornodes. The distributed file system is kept coordinated and synchronizedacross nodes by underlying Apache ZooKeeper services that are well knownin the art (see, e.g., component 601 in FIG. 6). However, ApacheZooKeeper does not teach content, organization, and/or arrangement ofthe distributed file system's constituent parts. According toembodiments of the present invention, the organization and arrangementof heartbeat monitoring distributed file system 545 is specific to andsuitable for the VM heartbeat monitoring systems disclosed herein, e.g.,node-to-node communications protocol based on data files distributedamong nodes; file system hierarchy; designating master, worker, andobserver roles; designating members of the quorum; indicating whichtarget VMs are assigned to which monitor node; indicating target VMsconfirmed failed; etc. See also FIGS. 7, 8, 9.

Heartbeat monitor nodes (e.g., 410, 1110, 1310, 1410) communicate witheach other by locally (on the monitor node) creating and updating datafiles (e.g., 712) that the underlying Apache ZooKeeper services (e.g.,601) coordinate and synchronize to the other monitor nodes within theillustrative distributed file system 545 as depicted by the solid boldbidirectional arrow. Thus, the data file 712 contents and the filesystem organization structure are proprietary to the illustrativeembodiments, while the inter-node coordination is handled by ApacheZooKeeper services 601. See also FIGS. 6, 8.

FIG. 6 is a block diagram illustrating certain functional components anda distributed file system that are configured in an illustrativeenhanced virtual server data agent configured as a heartbeat monitornode. FIG. 6 depicts: enhanced virtual server data agent 542, whichcomprises VM heartbeat monitoring framework 600, which in turn comprisesa number of functional components: Apache ZooKeeper 601, node-to-nodecommunications module 602, cloud-to-cloud support logic 604, master nodeselection logic 606, VM distribution logic 608, ping monitoring logic610, and heartbeat monitoring distributed file system 545. In somealternative embodiments, one or more of these functional components aredormant or absent, depending on the implementation needs, e.g., nocloud-to-cloud support logic 604 needed when source and destination areconventional data centers not cloud-based.

An instance of heartbeat monitoring distributed file system 545 isconfigured in each heartbeat monitor node (e.g., 410, 1110) thatexecutes enhanced virtual server data agent 542 as shown in the presentfigure. See also FIGS. 7, 8, 9. Logically, heartbeat monitoringdistributed file system 545 is part of VM heartbeat monitoring framework600.

VM heartbeat monitoring framework 600 represents a logical envelope forproviding VM heartbeat monitoring services according to an illustrativeembodiment. Thus, configuring a computing platform (e.g., VM, computingdevice, etc.) with an enhanced virtual server data agent 542 thatcomprises VM heartbeat monitoring framework 600 enables the computingplatform to operate as a heartbeat monitor node, whether in a master,worker, and/or observer role, and whether at a source, destination, orother neutral site that is neither source nor destination for VMfailover/failback purposes (e.g., cloud computing resources 303).

Apache ZooKeeper services 601 is a functional component of VM heartbeatmonitoring framework 600 that comprises an Apache ZooKeeper servicesinfrastructure, which is well known in the art and which enables highlyreliable distributed coordination among a plurality of nodes. See, e.g.,https://zookeeper.apache.org/. “ZooKeeper is a centralized service formaintaining configuration information, naming, providing distributedsynchronization, and providing group services. All of these kinds ofservices are used in some form or another by distributed applications.”https://zookeeper.apache.org/. “ZooKeeper aims at . . . a very simpleinterface to a centralized coordination service. The service itself isdistributed and highly reliable. Consensus, group management, andpresence protocols will be implemented by the service so that theapplications do not need to implement them on their own. Applicationspecific uses of these will consist of a mixture of specific componentsof Zoo Keeper and application specific conventions.”https://cwiki.apache.org/confluence/display/ZOOKEEPER/Index. Theillustrative heartbeat monitor nodes (e.g., 410, 1110) compriseapplications that are built on top of Apache ZooKeeper services designedto take care of inter-monitor-node coordination. For example, theillustrative heartbeat monitoring distributed file system 545 is basedon underlying Apache ZooKeeper services infrastructure. Illustratively,monitor nodes that are designated to be members of quorum 440 runZooKeeper server and client services; on the other hand, monitor nodesthat are designated to be workers but not members of quorum 440 needonly run ZooKeeper client services, though the invention is not solimited.

Node-to-node communications module 602 is a functional andorganizational component of VM heartbeat monitoring framework 600 thatcomprises functionality for communicating information among theillustrative heartbeat monitor nodes (e.g., 410). For example,node-to-node communications module 602 uses the illustrative protocoldepicted in FIG. 8 to organize information and populate illustrativedata file 712 therewith. Apache ZooKeeper takes care of coordinating thedistribution of data files 712 to all monitor nodes via distributed filesystem 545. See also FIGS. 7, 8.

Cloud-to-cloud support logic 604 is a functional component of VMheartbeat monitoring framework 600 that comprises functionality forspecially configuring components so that VM heartbeat monitoring andfailover/failback can be supported across two or more distinct cloudregions (e.g., Amazon web services region 1 versus Amazon web serviceregion 2), i.e., when source and destination are each implemented in acloud-based computing resource rather than as a conventional datacenter. See also FIGS. 13, 14.

Master node selection logic 606 is a functional component of VMheartbeat monitoring framework 600 that comprises functionality forestablishing a master monitor node within quorum 440 in collaborationwith storage manager 340. See also FIG. 16.

VM distribution logic 608 is a functional component of VM heartbeatmonitoring framework 600 that comprises functionality for determiningwhich target VM(s) in the illustrative data storage management systemare to be monitored by which heartbeat monitor node (e.g., 410, 1110).VMs that are targeted for heartbeat monitoring are “distributed” tosuitable heartbeat monitor nodes according to certain rules applied byVM distribution logic 608. See also FIGS. 6A, 17, 18.

Ping monitoring logic 610 is a functional component of VM heartbeatmonitoring framework 600 that comprises functionality whereby a givenheartbeat monitor node pings its target VMs to determine whether theyare operational. According to the illustrative embodiments, a heartbeatmonitor node that is designated a “worker” node executes theillustrative ping monitoring logic 610 relative to the target VMsassigned thereto by illustrative VM distribution logic 608. A node thatis designated a master also can operate as a worker node in someembodiments. Observer nodes do not operate as worker nodes according tothe illustrative embodiments. See also FIGS. 19, 20, 20A.

The abovementioned components of VM heartbeat monitoring framework 600are shown here as distinct elements to ease understanding of the variousfeatures. However, an implementation need not be so limited, andtherefore these components can be combined into one or more integratedgroupings without limitation. In some embodiments, the illustrativeenhanced virtual server data agent 542 need not include and/or need notactivate all these components when they are not needed, e.g., lackingcloud-to-cloud support logic 604 when source and destination are notcloud-based; lacking ping monitoring logic for heartbeat monitor nodesconfigured as observers; deactivating VM distribution logic in nodesthat are outside the quorum and thus will not be candidates for masterrole; etc.

FIG. 6A is a block diagram illustrating a logical view of VMdistribution logic 608 (part of VM heartbeat monitoring framework 600not shown here). FIG. 6A comprises: storage manager 340 comprisingmanagement database 346; VM host/server 401 hosting VMs 411 andhypervisor 520; heartbeat monitor node 410 designated to operate as a“master” and comprising validated target-VM list 6120, validatedworker-VM list 6121, and VM distribution rules 6122; target VM list6102; workers list 6104; validate operation 6106; and worker-to-VMmapping 6130. This block diagram is a logical representation intended toease understanding of how VM distribution logic 608 operates within theillustrative data storage management systems herein. VM distributionlogic 608 is a functional component of VM heartbeat monitoring framework600 (not shown in the present figure) is executed by a particularheartbeat monitor node 410 which has emerged as the master node asdescribed in more detail in blocks 1504 and 1510 (see, e.g., FIG. 15).VM distribution logic 608 determines which VMs defined as heartbeatmonitor targets are to be monitored by which suitable heartbeat monitornode (e.g., 410, 1110). The unidirectional arrows depict a logical flowof operations, ultimately resulting in the illustrative worker-to-VMmapping 6130, which indicates a set of target VM(s) assigned to eachheartbeat monitor node that operates as a worker. In general, theobjective of VM distribution logic 608 is for a given target VM (e.g.,411) to be distributed (assigned to) a heartbeat monitor node that ismore suitable that other heartbeat monitor nodes to perform pingmonitoring of the given target VM, such as assigning a heartbeat monitornode that is more logically proximate to the target than other monitornodes. Logical proximity (e.g., in the same VM network and host server,fewer hops, etc.) ensures less communication burden between monitor nodeand target, as well as better responsiveness by the monitor node whenthe target VM fails. VM distribution rules are discussed in more detailin FIG. 18.

Target VM list 6102, which is initially administered into and stored inmanagement database 346 is a first element for consideration. Target VMlist 6102 identifies all VMs 411 that are to be subjected to heartbeatmonitoring according to the illustrative embodiments. Notably, everyproduction VM 411 that operates in system 300 need not be designated asa target for VM heartbeat monitoring, since some VMs of relatively lowimportance will not require the resources needed for ongoing heartbeatmonitoring.

Workers list 6104, which is initially administered into and stored inmanagement database 346 is another element for consideration. Workerslist 6104 identifies all nodes in system 300 that are designated asheartbeat monitor worker nodes. Notably, any number of monitor nodes areVMs such as heartbeat monitor node 410-1 in FIG. 5, and any number arecomputing devices such as heartbeat monitor node 410-2 in FIG. 5, in anycombination without limitation. There is no limit on the total number ofheartbeat monitor nodes in system 300, and likewise there is no limit onhow many heartbeat monitor nodes are designated workers. See also FIG.10.

Validate operation 6106 receives target VM list 6102 and/or workers list6104 as inputs. Validate operation 6106 is executed by VM distributionlogic 608 to determine whether the VMs as identified in the administeredlists 6102 and 6104 are actually operational in system 300 according torespective hypervisor(s) 520 in one or more VM host/servers such as 401,402, etc. Typically, a hypervisor 520 is queried by VM distributionlogic 608 according to techniques well known in the art and in responsereports on active VMs executing over the said hypervisor 520. Aftercomparing the administered lists 6102 and 6104 against the reportsreceived from hypervisor(s) 520, VM distribution logic 608 generates arespective validated target-VM list 6120 and a validated worker-VM list6121. In alternative embodiments, these lists are consolidated into asingle data structure or are otherwise shown as validated, withoutlimitation, so long as the VMs are verified to be operational.

Once the validated lists 6120 and 6121 have been created, VMdistribution logic 608 applies VM distribution rules 6122 to assign eachactive target VM to a suitable “worker” heartbeat monitor node (e.g.,410-1, 410-2, 1110) that will be responsible for ping monitoring thetarget VM. See also FIG. 18. The result of applying VM distributionrules 6122 to the validated VM list 6120 is a worker-to-VM mapping 6130in which each worker heartbeat monitor node (whether VM-based 410-1 orcomputing device-based 410-2) has an assigned set of one or more targetVMs. There is no limit on how many target VMs are assigned to a givenworker node. Illustratively, worker-to-VM mapping 6130 is a datastructure stored in master monitor node 410, but in alternativeembodiments it is instead and/or in addition stored to managementdatabase 346.

The information in the worker-to-VM mapping 6130 that results fromexecuting VM distribution logic 608 at the master node is thendistributed to the respective worker nodes using the illustrative VMheartbeat monitoring distributed file system 545, e.g., using data file712. When changes to worker-to-VM mapping 6130 occur, e.g., due to afailover operation and/or changes in master/worker/observer node roles,the changes are likewise distributed using the illustrative VM heartbeatmonitoring distributed file system 545 and changes are detected usingthe watch processes implemented therein. See also FIGS. 7, 8, 9.

An illustrative process for VM distribution is described in more detailin FIGS. 17 and 18 herein, as well as in U.S. Provisional PatentApplication Ser. No. 62/402,269, filed on Sep. 30, 2016 and entitled“Heartbeat Monitoring of Virtual Machines for Initiating FailoverOperations in a Data Storage Management System,” which is incorporatedby reference herein. The illustrative VM distribution process comprisesa number of threads to reach the point wherein the resultingworker-to-VM mapping 6130 is generated. Three such threads are describednext, including VM Distribution Main thread, VM Distribution Back Endthread #1, VM Distribution Back End thread #2, and many VM DistributionWorker threads. VM Distribution Worker threads count varies with thenumber of VMs to distribute. Illustrative default number of VMdistribution worker threads is five and maximum is ten. Communicationamong threads is accomplished via six illustrative synchronized queues.Each synchronized queue is filled with VM Info data structure 808 fromthe heartbeat messaging protocol (see, e.g., FIG. 8). An illustrativeMaster thread communicates with the VM Distribution Main thread, VMDistribution Back End thread #1 and VM Distribution Back End thread #2with the help of vmQueue1, vmQueue2, vmQueue3. VM Distribution Mainthread communicates with each of the VM Distribution Worker threads byvmQueue1 (worker thread). VM Distribution Back End thread #1communicates with each of the VM Distribution Worker threads by vmQueue2(worker thread) and VM Distribution Back End thread #2 communicates witheach of the VM Distribution Worker threads by vmQueue3 (worker thread).

Each VM Distribution Thread illustratively performs the following tasks.

VM Distribution Main thread first gets the target VM list 6102 andWorkers list 6104 by contacting storage manager 340 and managementdatabase 346. Data center discovery follows, to validate these listsagainst actual operational hypervisor (e.g., 520) information. If agiven VM is powered off or not eligible for monitoring it will befiltered out of the validated VM list 6120. Workers also are validatedfor their respective power states. Information such as UUID, subnets,hosts, network adapters, known networks and switches are gathered forall VMs and workers from the data center discovery query. If the workeris an unvirtualized computing device (e.g., 501) then BIOS UUID,subnets, network adapters and switches are gathered by contacting thecomputing device's underlying operating system. This information is thenupdated in two illustrative local synchronized maps (VMInfo map,Workerinfo map) (not shown here). VM Distribution Main thread thenupdates the VMInfo data associated with a given monitor node in datastructure 802 in the heartbeat messaging protocol (e.g., data file 712)and updates the vmQueue1 (worker thread). After computation of theworker-to-VM mapping 6130, VM Distribution Main thread updates this mapto the master monitor node (e.g., data file 712 in/Master 702 indistributed file system 545—see, e.g., FIG. 7). The master monitor nodewill then distribute the individual target VM assignments to therespective /Worker nodes (e.g., VM heartbeat info data structure 802).

VM Distribution Worker threads compute the worker-to-VM mapping 6130,e.g., by applying VM distribution rules 6122 to the appropriate targetVMs in VM distribution list 6120 obtained from the vmQueue1 (see alsoFIG. 18). The number of concurrent VM distribution worker threads varieswith the number of target VMs to distribute (illustrative default beingfive). If the target VMs number over a thousand, then illustrativelyconcurrent VM distribution worker threads rises up to ten.

VM Distribution Back End Thread #1 distributes a few VMs in case of anyworker failures. The master monitor node distributes a failed worker'starget VMs (“orphaned target VMs”) to another healthy worker(s). Thisback end thread runs continuously and master thread will communicatewith the VMs to re-distribute by filling up vmQueue2. This thread getsthe orphaned target VMs to re-distribute from the vmQueue2 andidentifies the currently alive workers at that point in time. Thisthread performs the data center discovery for the orphaned target VMsand alive workers to validate. This thread then filters out ineligibleor failed orphans. This thread then updates the VMInfo data in vmQueue2(worker thread) to communicate to the VM Distribution Worker threads.After the computation of worker-to-VM mapping 6130 by the VMDistribution Worker threads, the mapping is updated to the mastermonitor node.

VM Distribution Back End Thread #2 is mainly used to perform dynamic VMre-distribution of VMs especially to workers chosen on the basis of hopcount and latency criteria—the chosen worker receiving all target VMs.Master thread receives this data with the help of heartbeat monitoringchange notification system. Master thread then updates this informationin the local maps VMinfo, Workerinfo synchronized maps. Master threadthen fills the vmQueue3 with the (Workerinfo, VMInfo) messagingstructure. VM distribution back end thread #2 receives the object(Workerinfo, VMInfo) messaging structure from the vmQueue3. This threadthen computes the best worker for a VM from the input object and localmaps VMInfo, Workerinfo. For example, if worker-1, worker-2, worker-3send VMinfo with hop counts 1, 2, 3, respectively, then the threadselects worker-1 with minimum hop-count as 1. Same goes with latencycalculations too. After this computation is done for all the VMs andworkers, the thread updates this information in the worker-to-VM mapping6130, which is then updated to the workers, e.g., via data file 712.

FIG. 7 depicts a hierarchical view of the illustrative distributed filesystem 545 comprising: root FS-node/VMHeartbeat 702; four subtendingFS-nodes including: /Failed_Masters 704, /Failed_Workers 706, /Quorum708, and/Master 720 comprising a data file 712; five/Quorum subtendingFS-nodes/Q_Node-n 710, each one comprising a data file 712; andthree/Master subtending FS-nodes /Worker-m 722, each one comprising adata file 712 and a subtending /Is_Alive flag. The illustrativedistributed file system 545 is based on underlying Apache ZooKeeperinfrastructure 601 which maintains the namespace and coordination ofinformation among heartbeat monitor nodes that each comprise an instanceof distributed file system 545. The term “file-system-node” or “FS-node”herein refers to aspects of the illustrative distributed file system545, including data structures (e.g., directories, files, hierarchicalrelationships) in distributed file system 545, which compriseinformation and/or represent certain entities in heartbeat monitoringsystem 300. In some alternative embodiments these FS-nodes are referredto as “ZooKeeper-nodes” or “Znodes” since they are implemented over theZooKeeper services infrastructure (e.g., 601). FS-nodes and Znodes aredistinguishable from the term “heartbeat monitor node” or “monitor node”such as components 410, 1110, 1310, 1410, which are functional operators(executing enhanced virtual server data agents 542) that are responsiblefor monitoring target VMs, such as according to exemplary method 1500 inFIG. 15. See also U.S. Provisional Patent Application Ser. Nos.62/402,269 and 62/604,988, which are incorporated by reference herein.

Heartbeat Monitoring Distributed File System 545 is built on top ofApache ZooKeeper services (e.g., 601) to store information and tocoordinate information among different heartbeat monitor nodes. Aninstance of distributed file system 545 is configured in each monitornode and is coordinated and synchronized by Apache ZooKeeper services601, which also ensures that any updates are processed in orderedfashion. The replication and synchronization tasks are performed byApache ZooKeeper services 601, thus advantageously leveraging thereliability of these basic services. The master monitor node creates thehierarchical tree-structured files in heartbeat monitoring distributedfile system 545 (see, e.g., block 1608). The root FS-node is the entrypoint of the file system. All other child FS-nodes prepend with thisroot designation.

Distributed file system 545 reflects in its constituent FS-nodesdifferent roles played by the heartbeat monitor nodes, and thereforedistinguishes between quorum membership, e.g., including an FS-node foreach master, worker, and/or observer in quorum 440 (e.g., FS-nodes 708and 710), versus master-worker hierarchy regardless of whether any givenworker is also in the quorum (e.g., FS-nodes 720 and 722) and/or whetherit is also the designated master monitor node. Thus, a heartbeat monitornode 410 that is in quorum 440, has been elected master, and alsooperates as a worker monitor node is represented by FS-node 710, FS-node720, and FS-node 722, respectively—thus representing each distinct rolewithin the distributed file system.

702. FS-node/VMHeartbeat 702 represents the highest-level or root of theillustrative distributed file system. Four subtending nodes aredepicted.

704. FS-node/Failed_Masters 704 subtends to FS-node/VMHeartbeat 702 andidentifies any heartbeat monitor node(s) 410 that were designated asmaster monitor nodes. This is a synchronized queue containing theprevious masters which participated in the heartbeat monitoring process.

706. FS-node/Failed_Workers 706 subtends to FS-node/VMHeartbeat 702 andidentifies any heartbeat monitor node(s) 410, 1110 that were designatedas worker monitor nodes but which subsequently failed. This is asynchronized queue depicting all the worker nodes which previously wentdown and currently are not participating in the heartbeat monitoringsystem.

708. FS-node/Quorum 708 subtends to FS-node/VMHeartbeat 702 and throughits subtending FS-nodes identifies any heartbeat monitor nodes 410 thatare designated as members of quorum 440. Illustratively, five suchquorum members are represented by subtending FS-nodes 710. Arepresentation of the entire state of the heartbeat monitoringapplication is stored in the/Master FS-node 708. This is useful in caseof current master's failure. After election of a new master, the newmaster monitor node gets the whole state of the heartbeat monitoringapplication by querying the heartbeat monitoring distributed file system545 so that the information can be reliably and rapidly recovered andavailable for use by the new master monitor node.

710. Five FS-nodes/Q-Node-1 . . . /Q_Node-5 710 subtend toFS-node/Quorum 708 and each represents a member of quorum 440, i.e.,represents a heartbeat monitor node 410 that participates in quorum 440,whether in the role of master, worker, and/or observer. Quorum 440illustratively comprises five monitor nodes as shown in FIG. 4, each ofwhich is represented in distributed file system 545 by anFS-node/VMHeartbeat/Quorum/Q_Node-1 . . . /Q_Node-5. EachFS-node/Q_Node-n comprises a respective data file 712, which among otherinformation identifies the operational heartbeat monitor node 410 thatis a member of quorum 440 and further identifies its designated role as“master,” “worker,” and/or “observer.” Illustratively, these areimplemented as so-called ephemeral FS-nodes, so that when a quorummember fails, its FS-node 710 vanishes, automatically deleted by ApacheZooKeeper (and this change is detected via a watch process 902—see alsoFIG. 9). When one or more members of the quorum fail, quorum 440 may beable to survive, depending on the severity of the failure(s), asdescribed in more detail in FIG. 10. Any number of heartbeat monitornodes 410 can be configured into quorum 440 and therefore can berepresented by corresponding FS-Nodes/Q_Node-n in distributed filesystem 545.

720. FS-node/Master 720 subtends to FS-node/VMHeartbeat 702 andcomprises a data file 712, which among other information identifies theoperational heartbeat monitor node 410 that is designated the masteramong the monitor nodes that form quorum 440. Heartbeat monitor nodesdesignated as workers are represented as subtending to the master, e.g.,722. /Master 720 represents the current master monitor node.

722. Three/Master subtending nodes /Worker-1 . . . /Worker-3 722 subtendto FS-Node/Master 720 and each represents a monitor node (e.g., 410,1110) that operates as a worker monitor node, i.e., executes pingmonitoring logic 610 relative to its respective list of target VMs 411.In FIG. 4, these three illustrative monitor nodes are shown in sourcedata center 301. Illustratively, the monitor node that is designatedmaster (“M”) additionally operates as a worker monitor node in theillustrative embodiments, thus having a dual role as both master ofquorum 440 and as a worker node responsible for monitoring its assignedtarget VMs (though this dual role is not required by the presentinvention). Therefore, the right-most depicted /Worker-3 722 datastructure represents the monitor node in its worker role, whereas/Master720 represents the self-same monitor node in its master role. EachFS-node /Worker-m comprises a respective data file 712, which amongother information identifies the operational heartbeat monitor node 410,1110 that is designated to operate as a worker heartbeat monitor node.

724. Subtending to each FS-node /Worker-m is a /Is_Alive 724 flag thattracks whether the respective heartbeat monitor note is operational or“alive.” These are illustratively implemented as ephemeral FS-nodes.Thus, if a worker monitor node fails, the corresponding worker's/Is_Alive FS-node 724 vanishes, automatically deleted by ApacheZooKeeper (and this change is detected via a watch process 924—see alsoFIG. 9).

As explained in further detail in FIG. 9, changes to these datastructures are detected within the distributed file system 545 via anumber of so-called “watch” processes that are implemented by the ApacheZooKeeper infrastructure 601. The heartbeat monitoring distributed filesystem 545 illustrated here is only one example of how to represent theVM heartbeat monitoring network of system 300 shown in FIG. 4. However,the invention is not so limited and in other embodiments distributedfile system 545 takes a different form/hierarchy for representing thesalient components and their distinctive roles.

FIG. 8 depicts a template for content of an illustrative data file 712used in illustrative distributed file system 545. As explained elsewhereherein (e.g., FIG. 7), data files 712 are generally used for storinginformation that pertains to certain salient components of system 300and thanks to the coordination and watch processes performed by theunderlying Apache ZooKeeper infrastructure 601, changes in a given datafile 712 stored in a given monitor node are communicated to other datafiles 712 in the other monitor nodes. An illustrative template ispresented here for storing information in a data file 712, including: VMheartbeat information 802, machine information 804, network information806, and VM information 808. Illustratively, file 712 is configured asan XML file, but the invention is not so limited. Thus, node-to-nodecommunications among heartbeat monitor nodes (e.g., 410, 1110, 1310,1410) uses the illustrative protocol embodied by data file 712 and itsconstituent parts depicted here.

VM heartbeat information data structure 802 (e.g., XML file) comprisesinformation about the monitor nodes that operate as master, worker(s),and observer(s) in system 300, using pointers as needs to some of theother data structures in file 712. Selected portions of Worker-to-VMmapping 6130 are stored in respective entries of VM heartbeatinformation data structure 802, so that the set of target VMs to bemonitored by a given worker monitor node is associated with thatworker's entry in the VM heartbeat information data structure 802.Illustratively, an entry for the master monitor node points to itscorresponding machine information. Illustratively, entries for eachworker monitor node point to the corresponding machine information, thetarget VM list assigned to the given worker monitor node (“All_VM”)(e.g., obtained from worker-to-VM mapping 6130), and a list of targetVMs that are confirmed failed (“Failed_VM”). Illustratively, entries forobserver monitor nodes point to the corresponding machine information.

Machine information data structure 804 (e.g., XML file) comprisesinformation about a particular machine (e.g., computing device 501, VMhost/server 401) that hosts a given master, worker, or observer monitornode. Illustrative information includes machine name, DNS (domain namesystem) name, IP address, universally unique identifier (UUID), hostname, power state (e.g., active, inactive), location, ranking based onnetwork information, etc., without limitation.

Network information data structure 806 (e.g., XML file) comprisesinformation about the data network in which a given machine belongs.Illustrative information includes network name, network label, whetherthe machine is connected, subnet identification (subnet in IP address),etc. without limitation.

VM information data structure 808 (e.g., XML file) comprises informationabout a particular target VM 411 assigned to a worker monitor node. Inthe case of replica VMs 421, information such as a Replica ID is alsoincluded to help correlate a production VM 411 with its correspondingreplica VM 421. Illustrative information includes VM name, DNS (domainname system) name, IP address, universally unique identifier (UUID),replica ID, host name, power state, pointer to network information,measure of latency, hop count, etc. without limitation.

The template illustrated here is only one example of how to representthe contents of a data file 712. However, the invention is not solimited and in other embodiments data file 712 takes a differentform/hierarchy for representing the salient information.

How the node-to-node communication protocol works for communicatingamong the illustrative heartbeat monitor nodes. The illustrative XMLstructure protocol of data file 712 is used by master and all workers inserialized format for inter-monitor-node communication purposes. If themaster monitor node has to send data to one or more worker monitor nodesit updates the “From” field in data structure 802 to “master” and makesother suitable changes in data file 712, e.g., a change in All_VM listfor a given worker. Worker nodes “receive” this message by detectingchanges to data file 712 via watch processes, e.g., 923, and then willprocess the updated content of data file 712. Likewise, if a workermonitor node has to send data to the master monitor node, the workerupdates the “From” field in data structure 802 to “worker ID” and makesother suitable changes in data file 712, e.g., updating its Failed_VMlist to indicate that certain of its target VMs are confirmed failed.Master “receives” this message by detecting changes to data file 712 viawatch processes, e.g., 922, and then will process the updated content asappropriate, e.g., notifying storage manager 340 to call failover forthe target VMs confirmed failed. Thus, updates to data files 712 providenode-to-node communications. Observer nodes likewise receive allupdates. Data file 712 is created/updated and stored to a local cache onthe computing device (e.g., 401, 501) that hosts the heartbeat monitornode. Apache ZooKeeper takes care of transmitting updated data files 712in a sequential and coordinated manner among all monitor nodes that arepart of distributed file system 545. Apache ZooKeeper further takes careof the watch processes that detect changes in the updated data files712. See also FIG. 9.

FIG. 9 depicts illustrative watch processes in heartbeat monitoringdistributed file system 545 of system 300. Apache ZooKeeperinfrastructure 601 comprises a so-called watch functionality that isused for detecting changes and change notification in a ZooKeeper-baseddistributed files system such as heartbeat monitoring distributed filesystem 545. “A watch event is a one-time trigger, sent to the [entity]that set the watch, which occurs when the data for which the watch wasset changes.”https://zookeeper.apache.org/doc/r3.4.5/zookeeperProgrammers.html#ch_zkWatches.Apache ZooKeeper watch setting and change detecting as well as theunderlying watch processes are well known in the art.

Accordingly, the unidirectional double-line arrows in the present figuredepict a number of Apache ZooKeeper watch processes that are active inthe illustrative VM heartbeat monitoring distributed file system 545.Watch processes enable the watching entities to become aware of changes(a “change detection and notification system”), effectively acting as acommunications protocol among heartbeat monitor nodes. In some cases,the detected changes will cause remedial action to be taken, e.g.,re-targeting ping monitoring to other target VMs, finding a new mastermonitor node, etc.

Watch processes 902 represent a scheme whereby each member of quorum 440watches for changes in a designated “neighbor” quorum node. The neighborneed not be geographically proximate. Watch processes 902 are concernedwith quorum integrity. When data file 712 in a watched Q_node changes orif the watched Q_node changes or the neighbor Q_node vanished (ephemeralFS-node), the watching “neighbor” quorum node becomes aware of thechange and triggers remedial action. Remedial action examples upon aquorum node failure include determining whether the quorum 440 can stillsurvive (see, e.g., FIG. 10), electing a new master monitor node (see,e.g., FIG. 16), changing a node's role from observer to worker,re-establishing “neighbor” watches in a surviving quorum scenario, etc.,without limitation.

Watch processes 922 enable the master monitor node to watch for changesin worker monitor nodes. Watch processes 922 are concerned withdetecting changes in worker nodes. Notably, not every worker monitornode needs be a member of quorum 440. Changes in a data file 712 thatresides in a /Worker FS-node (e.g., in /Worker-1) will be detected by/Master via a watch process 922 and may, if necessary, result inremedial action, e.g., a change in network topography may require areset, an addition to a worker's Failed_VM list in data structure 802requiring notice be sent to storage manager 340 to call failover, etc.,without limitation.

Watch processes 923 enable each worker monitor node to monitor itselffor relevant changes, e.g., after a re-distribution of target VMs asreflected in data structure VM heartbeat information 802 of data file712, and further acts as a way of each worker detecting changesdistributed by the master monitor node via data file 712. Based on arevised list of target VMs (All_VM)—typically promulgated by the mastermonitor node after executing VM distribution logic 608—a given workermonitor node would detect the change via watch process 923 and wouldre-target its ping monitoring. Some detected changes may not triggeraction at the watching worker monitor node, e.g., when another worker'slist of target VMs changes without affecting the watching worker.

Watch processes 924 enable the master monitor node to watch forvanishing “Is_Alive” flags 724 at its worker nodes. Watch processes 924are concerned with worker integrity. A disappearance of a watched/Is_Alive FS-node 724 (implemented as an ephemeral FS-node) indicates tothe watching master monitor node that the watched worker node hasfailed, necessitating remedial action, such as re-distributing VMs usingVM distribution logic 608 (see, e.g., FIG. 21).

Watch processes 932 enable the master monitor node to watch for anddetect changes in a list of failed masters. The Failed_Masters list maybe maintained for historical and reporting purposes, e.g., when a givenmaster monitor node failed.

Watch processes 933 enable the master monitor node to watch for anddetect changes in a list failed worker nodes. The Failed_Workers listmay be maintained for historical and reporting purposes, e.g., when agiven worker node failed.

The watch processes depicted here are suitable to the illustrative VMheartbeat monitoring distributed file system 545, but are not limiting.Other watches can be established by the implementers of a VM heartbeatmonitoring network according to the present invention, withoutlimitation.

FIG. 10 depicts illustrative quorum 440 arrangements for heartbeatmonitor nodes. Four scenarios are depicted—labeled A, B, C, and D.

In scenario A, an illustrative arrangement for a quorum 440 is depictedas shown in FIG. 4. Accordingly, a master monitor node and two workermonitor nodes are configured in source data center 301; an observermonitor node is configured in destination data center 302; and anobserver monitor node is configured in cloud-based computing resources303. Thus, quorum 440 comprises five quorum nodes, of which the majorityof three is configured in the source data center 301.

Scenario B depicts two failed worker nodes at the source data center 301of scenario A. The failed worker nodes have been replaced by a workernode in destination data center 302 (previously merely operating as anobserver node in scenario A), resulting in a working quorum 440comprising only three working quorum nodes. If the master monitor nodein source data center 301 were to fail also (e.g., catastrophic failureat the source data center), quorum 440 would fail altogether, as onlytwo of five quorum nodes would still be operational. A complete reset ofthe VM heartbeat monitoring system 300 would be necessary tore-establish a working arrangement and configuration of quorum nodes, aswell as suitable worker nodes able to handle the VM heartbeat monitoringof target VMs. Scenario B thus demonstrates a weakness in configuring amajority of quorum nodes at the source data center, since a catastrophicfailure at the source will take down quorum 440 and the VM heartbeatmonitoring infrastructure. Scenarios C and D present an alternative andmore robust approach.

In scenario C, an illustrative arrangement for a quorum 440 is depicted.A master monitor node and one worker monitor node are configured insource data center 301; two observer monitor nodes are configured indestination data center 302; and an observer monitor node is configuredin cloud-based computing resources 303. Thus, quorum 440 comprises fivequorum nodes, of which the majority of three is configured outside ofthe source data center 301.

Scenario D depicts a failed master monitor node and a failed workermonitor node at the source data center 301 of scenario C, as depicted inFIG. 12. The failed nodes have been replaced by a master and a workernode in destination data center 302 (previously merely operating asobserver nodes in scenario C). Quorum 440 survives this catastrophicfailure at the source data center 301, because the majority of quorumnodes are configured and remain operational elsewhere. Therefore, thisarrangement of quorum nodes is more robust than the arrangement ofscenario A and FIG. 4. Notably, one or more other worker monitor nodescan be configured in source data center 301 to handle the load ofmonitoring any number of target VMs there, but if these other workermonitor nodes are not part of quorum 440, the quorum can survive thecatastrophic failure of data center 301 and re-establish appropriatefailover monitor nodes at the destination data center 302. Likewise, anynumber of worker monitor nodes can be configured at destination datacenter 302 without making these nodes part of quorum 440.

The configuration scenarios for quorum 440 shown here are illustrativeand the invention is not so limited. Any number of quorum nodes may beconfigured in any arrangement suitable to the implementers of a VMheartbeat monitoring system according to the present invention.Likewise, any number of additional worker nodes that are not quorummembers also may be configured.

FIG. 11 is a block diagram illustrating failover of target VMs toreplica VMs and to another monitor node(s) in system 1100. FIG. 11depicts a system 1100, which is analogous to system 300 in FIG. 4 withsome exceptions: some target VMs 411 at source data center 301 havefailed over to replica VMs 421 at destination data center 302;destination data center 302 comprises a worker monitor node 410 thatheld an observer role in quorum 440 in FIG. 4 when replica VMs 421 wereinactive and is now activated as a worker monitor node for certainreplica VMs 421 (solid unidirectional arrow); destination data center302 further comprises another worker monitor node 1110 that activelymonitors some of replica VMs 421 (solid unidirectional arrow). As inFIG. 4, all monitor nodes 410, 1110 are in communication with storagemanager 340 but for simplicity not all such communicative couplings areshown in the present figure by dotted bidirectional arrows.

Failover of a failed VM is called and managed by storage manager 340according to technology known in the art, but the technology wherebystorage manager 340 reaches the point of calling failover for a given VMis performed according to the illustrative embodiments disclosed herein,including the VM heartbeat monitoring network shown here comprisingmonitor nodes 410 and 1110. See also FIG. 15.

Heartbeat monitor node 1110 is analogous to heartbeat monitor nodes 410(e.g., executing an enhanced virtual server data agent 542), but node1110 is not configured to be part of quorum 440. Node 1110 is configuredas a worker monitor node with a set of target VMs to monitor, and node1110 is subtending to a master monitor node 410 (e.g., node 410 “M W”shown here in source data center 301). Node 1110, like otherillustrative heartbeat monitor nodes 410, participates in the heartbeatmonitoring distributed file system 545, wherein it is represented by acorresponding FS-node 722. Accordingly, the dashed bidirectional arrowdepicts a communication pathway between node 1110 and another heartbeatmonitor node 410 (e.g., in destination data center 302).

However, monitor node 1110 is not part of quorum 440 and is not involvedin quorum operations such as selecting a new master monitor node andwatching a “neighbor” quorum node—and thus node 1110 is not representedin distributed file system 545 by a FS-node 710. Like other heartbeatmonitor nodes, node 1110 is in communication with storage manager 340 asdepicted by the dotted bidirectional arrow between them.

The present figure is only one example scenario of VM failover accordingto an illustrative embodiment of the present invention, but otherembodiments are possible. Other embodiments support not only failover oftarget production VMs (e.g., 411) to replica VMs (e.g., 421), but alsosupport failback from target VMs 421 back to target VMs 411. Moreover,failover of heartbeat monitor nodes (e.g., 410, 1110) also is supportedas described in further detail elsewhere herein. The present inventionimposes no limits on the number of production VMs 411, replica VMs 421,heartbeat monitor nodes (e.g., 410, 1110), size of quorum 440, datacenters (e.g., 301, 302, 303), and failover/failback operations.

FIG. 12 is a block diagram illustrating a system 1200 experiencingfailure of the entire source data center, according to an illustrativeembodiment of the present invention. System 1200 is analogous to system300 in FIG. 4 with some exceptions: all of source data center 301 hasfailed, including the two heartbeat monitor nodes 410 therein and theproduction VMs; quorum 440 survives (bold bidirectional arrows) with twomonitor nodes 410 (one master, one worker) at the destination datacenter 302 and one monitor node 410 (observer) at cloud-based computingresources 303; replica VMs 421 have been activated on failover and arenow active target VMs being monitored by the two heartbeat monitor nodes410 in destination data center 402 (solid unidirectional arrows). Theoperational heartbeat monitor nodes 410 are in communication withstorage manager 340 (dotted bidirectional arrows).

The present figure is only one example scenario of data center failoverthat includes failed production VMs and heartbeat monitor nodes thereofaccording to an illustrative embodiment of the present invention. Otherembodiments also support failback from destination data center 302 backto source data center 301. The present invention imposes no limits onthe number of production VMs 411, replica VMs 421, heartbeat monitornodes (e.g., 410, 1110), size of quorum 440, data centers (e.g., 301,302, 303), and failover/failback operations.

FIG. 13 is a block diagram illustrating a system 1300 for heartbeatmonitoring of virtual machines for initiating cloud-to-cloud failoverand/or failback operations, according to an illustrative embodiment ofthe present invention. System 1300 comprises: storage manager 340; cloudregion 1303-1 comprising production VMs 411, two worker monitor nodes410, and one master monitor node 1310; cloud region 1303-2 comprisingreplica VMs 421, one observer monitor node 410, and another observermonitor node 1310. Quorum 440 comprises the five aforementioned monitornodes.

According to the illustrative embodiment depicted here, VMs that operatein a public cloud are monitored and failed over from cloud region 1 tocloud region 2, and vice-versa. Public clouds are generally known in theart and are understood to mean cloud based computing resources providedby a cloud service provider such as Amazon Web Services or MicrosoftAzure or any other similar provider, without limitation. Because VMsoperate in a third party-provided public cloud, the user and/oradministrator of the illustrative VM heartbeat monitoring system 1300has limited access to and limited control over the underlying computingresources at these public cloud data centers, which leads to certainsecurity concerns and enhancements in the illustrative componentsdescribed herein.

In contrast to data centers 301 and 302, wherein every heartbeat monitornode is in communication with storage manager 340 (see, e.g., FIG. 4),security concerns prevent such a communication pattern in thecloud-based data centers here. Therefore, communications with storagemanager 340 are managed through a firewall function (“FW”) that isactivated at the master monitor node 1310 in the source region 1303-1and also at an observer monitor node 1310 in the destination region1303-2. Accordingly, the master monitor node 1310 at source region1303-1 acts as a gateway to storage manager 340 and tunnels allcommunications between storage manager 340 and the other heartbeatmonitor nodes 410 operating in source region 1303-1.

To account for the possibility that the master monitor node may fail andbe replaced by another heartbeat monitor node at source region 1303-1,it is advantageous to enable a rapid and automatic process that can takehold with no or minimal administrator intervention in case the presentmaster fails. Accordingly, cloud-to-cloud support logic 604 (see, e.g.,FIG. 6) provides an enhanced firewall feature that opens certain portson the other (non-master) heartbeat monitor nodes 410, so that uponbeing elected a new master, a heartbeat monitor node with the open portscan immediately establish communications with storage manager 340 andtake over the firewall function in cloud region 1303-1. Thus, it can besaid that master monitor node 1310 comprises the enhanced firewallfeature that opens other monitor nodes' ports for secure communicationswith storage manager 340. Likewise, cloud-to-cloud support logic 604executing in observer monitor node 1310 at destination region 1303-2also comprises this enhanced firewall feature so that destination region1303-2 can smoothly transition in case of a failover thereto, includinga partial failure or a total failover from region 1303-1. Accordingly,the enhanced firewall feature will automatically open certain ports onthe other heartbeat monitor nodes 410/1110 at destination region 1303-2,so that a heartbeat monitor node with the open ports can immediatelyestablish communications with storage manager 340 and take over thefirewall function if need be. Although the ports are set open by theenhanced firewall feature, communications with storage manager 340 aredisabled so long as another heartbeat monitor node carries on the masterrole.

Upon notice received by storage manager 340 that a target VM or aheartbeat monitor node has failed (received from the master monitornode), storage manager 340 will manage failover operations for thefailed VM(s) and/or monitor node(s), including failovers from one cloudregion to the other region (e.g., 1303-1 to 1303-2).

Cloud regions 1303 (e.g., 1303-1, 1303-2) are logically distinctsections of public cloud computing resources of a cloud service provider(e.g., Microsoft Azure, Amazon Web Services (AWS), etc., withoutlimitation). Though offered by the same cloud services provider, thesedistinct cloud regions behave as mutually independent cloud-basedcomputing resources, and therefore must be treated by the illustrativeembodiment as respectively distinct source and destination data centersfor purposes of VM heartbeat monitoring and failover/failbackoperations. Thus, one region (e.g., 1303-1) comprises production VMs 411and is treated as the source data center, whereas the other region(e.g., 1303-2) comprises replica VMs 421 and is treated as a destinationdata center. Accordingly, cloud-to-cloud failover enablingcloud-to-cloud failover (e.g., from region 1303-1 to region 1303-2) andcloud-to-cloud failback enabling cloud-to-cloud failover (e.g., fromregion 1303-2 to region 1303-3) is enabled—and as in other illustrativeembodiments, storage manager 340 calls failover/failback and manages theoperations therefor.

Heartbeat monitor nodes 1310 are analogous to heartbeat monitor nodes410 (e.g., part of quorum 440, designated as master and observerrespectively) and further comprise a firewall function (e.g., CommvaultFirewall). The firewall function, which is generally known in the art,blocks unauthorized access to portions of system 1300 that operate in agiven region (e.g., 1303-1) from any components outside the givenregion. Thus, communicative couplings (dotted bidirectional arrows) fromthe given cloud region with storage manager 340 and the other cloudregion (e.g., 1303-2) are funneled through the region's firewallcomponent, e.g., heartbeat monitor node 1310—and vice-versa relative tocloud region 1303-2. Communications between other, non-firewalledmonitor nodes 410 and storage manager 340 are directed through (funneledvia) the firewalled component 1310 (dotted bidirectional arrows).

Component 1310 in cloud region 1303-1 also performs as a heartbeatmonitor node, illustratively as a member of quorum 440, as a mastermonitor node, and also as a worker monitoring certain target VMs 411(solid unidirectional arrow). Component 1310 in cloud region 1303-2 isalso a member of quorum 440 and is currently carrying on an observerrole—though after a failover it could become a master and possibly alsoa worker monitoring certain replica VMs 421.

The present figure is only one example configuration enablingcloud-to-cloud failover and/or failback (e.g., from region 1303-1 toregion 1303-2 and vice-versa) according to an illustrative embodiment ofthe present invention. The present invention imposes no limits on thenumber of production VMs 411, replica VMs 421, heartbeat monitor nodes(e.g., 410, 1110, 1310), size of quorum 440, number of cloud regions(e.g., 1303-1, 1303-2) and failover/failback operations.

FIG. 14 is a block diagram illustrating a system 1400 for heartbeatmonitoring of VMs for initiating cloud-to-cloud failover and/or failbackoperations using an integrated storage manager and heartbeat monitornode 1410, according to an illustrative embodiment of the presentinvention. System 1400 comprises: cloud region 1303-1 comprisingproduction VMs 411, two worker monitor nodes 410, and one integratedmaster monitor node plus storage manager 1410; cloud region 1303-2comprising replica VMs 421, one observer monitor node 410, and anotherobserver monitor node 1310. Quorum 440 comprises the five aforementionedmonitor nodes.

Component 1410 comprises the functionality of (a) a heartbeat monitornode and firewall 1310, and (b) a storage manager 340 (e.g., storagemanager software, firewall, and enhanced virtual server data agent 542executing on the same computing device host comprising one or moreprocessors and suitable computer memory. Thus, component 1410 providesfirewall protection to the components of system 1400 inside cloud region1303-1. Component 1410 also acts as the storage manager of system 1400(including management database 346 not shown here). Communicationsbetween heartbeat monitor nodes 410 inside cloud region 1303-1 and thestorage manager of component 1410 are not shown here. Component 1410also performs as a heartbeat monitor node, illustratively as a member ofquorum 440, as a master monitor node, and also as a worker monitoringcertain target VMs 411 (solid unidirectional arrow).

Communications between heartbeat monitor nodes (e.g., 410, 1110, 1310)in cloud region 1303-2 and the storage manager of component 1410 arefunneled via the firewalled monitor node 1310 (dotted bidirectionalarrow).

The present figure is only one example configuration enablingcloud-to-cloud failover and/or failback (e.g., from region 1303-1 toregion 1303-2 and vice-versa) according to an illustrative embodiment ofthe present invention. In other embodiments, a standby storage manageris configured in the destination region (e.g., 1303-2) as a failoverdestination for the storage manager in component 1410 in cloud region1303-1, whether as a stand-alone component such as 340 or as anintegrated component such as 1410. The present invention imposes nolimits on the number of production VMs 411, replica VMs 421, heartbeatmonitor nodes (e.g., 410, 1110, 1310), size of quorum 440, number ofcloud regions (e.g., 1303-1, 1303-2) and failover/failback operations.

FIG. 15 is a flow chart illustrating a method 1500 for performingvirtual machine heartbeat monitoring in a data storage managementsystem, according to an illustrative embodiment of the presentinvention. One or more components of illustrative systems 300, 1100,1200, 1300, and/or 1400 execute the operations of method 1500 asdescribed in further detail below and elsewhere herein. Components withan operational enhanced virtual server data agent 542 and whichsuccessfully execute VM heartbeat monitoring framework 600 therein alsoexecute the Apache ZooKeeper infrastructure 601, which coordinates amongmonitor nodes and maintains the heartbeat monitoring distributed filesystem 545 (e.g., keeping watches 900, transmitting data files 712 amongnodes, etc.).

At block 1502, a variety of preliminary administrative and activationoperations take place in the system. These operations include withoutlimitation: VM administration; VSDA 542 activation on VMs and/orcomputing devices configured as heartbeat monitor nodes (see, e.g., FIG.5); designating which nodes are to be part of quorum 440; and any otheradministrative and activation operations that are needed for activatingdata centers 301, 302, 303, 1303-1, 1303-2, etc. and storage manager340/1410.

At block 1504, monitor nodes designated to be in quorum 440 executemaster node selection logic 606, designating an initial or new mastermonitor node, worker nodes(s), and observer node(s). See also FIG. 16.

At block 1506, which is a decision point, storage manager 340 determineswhether the VM/computing device host for the master monitor node isoperational. If not, control passes back to block 1504 for findinganother master monitor node. If the host is operational, then controlpasses to block 1508.

At block 1508, which is a decision point, storage manager 340 determineswhether VSDA services for heartbeat monitoring are running on the hostof the master monitor node, i.e., is framework 600 operational inenhanced virtual server data agent 542? If not, the “neighbor” watchingquorum node is notified of the master node's failure (e.g., using watch902 which detects the vanishing of the master's Q_node 710 indistributed file system 545). According to the illustrative embodiment,the “neighbor” node that watched the failed master is the monitor nodethat is first to launch master selection logic 606 as described at block1612 in FIG. 16. Of course, the rank of this first node may beunsuitable for its being elected master, in which case a next adjacentquorum node is considered, thus ultimately identifying a quorum memberof sufficiently low rank to qualify as a proper master monitor node. Seealso FIG. 16. Control passes back to block 1504. If operational, themaster monitor node is deemed to be healthy and control passes to block1510.

Block 1510 comprises operations executed by the (healthy) master monitornode, including VM distribution logic and VM failover notice to thestorage manager, as described in further detail in another figure herein(see, e.g., FIG. 17).

At block 1512, which is a decision point, storage manager 340 determineswhether each worker node is operational as a monitor node (i.e.,operational host executing VSDA 542 running VM heartbeat monitoringframework 600). If not, control passes to the master monitor node forappropriate backstop operations at block 1518. If operational, controlpasses to block 1516.

Block 1516 comprises operations executed by each worker monitor node(including worker operations performed by a master monitor node that isalso configured as a worker), including ping monitoring of target VMsand VM failure confirmation—as described in further detail in anotherfigure herein (see, e.g., FIGS. 19, 20A).

Block 1518 comprises so-called backstop operations performed by themaster monitor node when one or more worker monitors node are down—asdescribed in further detail in another figure herein (see, e.g., FIG.21).

The present figure provides only an illustrative framework for VMheartbeat monitoring for initiating failover and/or failback operationsin a data storage management system. A number of variations arecontemplated, depending on the actual configuration of the system inwhich method 1500 executes, e.g., 300, 1100, 1200, 1300, 1400, etc.without limitation. Although the term “failover” is used here, it is tobe understood that failback operations are also included when a targetVM at a former destination data center fails back to a VM in the formersource data center. Thus after switching roles, a failover destinationis the failback source and a failover source is the failbackdestination.

FIG. 16 is a flow chart illustrating certain salient operations of block1504 in method 1500. Block 1504 is generally directed at masterselection logic being executed by quorum 440 member nodes (e.g., 410,1310, 1410).

At block 1602, based on administrative parameters in storage manager 340(e.g., stored in management database 346) in which certain nodes weredesignated to be part of quorum 440, a quorum node is selected that hasminimum rank based on the node's location (source, destination, cloud)to execute a master selection thread. Illustratively, storage manager340 finds a quorum node with a minimum rank (i.e., at the source datacenter) and notifies it to begin executing a master selection thread,thus becoming the first master candidate. As noted earlier, a quorumnode can run on a nonvirtualized computing device (e.g., 410-2), or on aVM (e.g., 410-1, 1310, 1410), without limitation. The selected node mayor may not ultimately emerge as the master monitor node, as describedbelow. The rank is computed based on the location of the selectedcandidate—a candidate in the source data center has a lower rank thancandidates in the destination data center 302 or cloud 303, andtherefore for an operational source data center, the first mastercandidate will be located at the source data center, e.g., 301. If thereare several candidates at the source data center, storage manager 340will arbitrarily choose one as the first candidate according to anillustrative embodiment, but the invention is not so limited.

At block 1604, other healthy designated quorum nodes launch a respectivemaster selection thread after the first candidate node launched itsmaster selection thread. Additionally, they will also poll storagemanager 340 to see if a master has already been elected. If a master hasbeen established, these other quorum nodes back off, terminating themaster selection thread; otherwise, they continue to process the masterselection thread until the master has been elected. Electing a masternode within a quorum is an Apache ZooKeeper feature well known in theart. However, polling storage manager 340 to determine whether a newmaster has emerged is not provided by Apache Zookeeper.

At block 1606, a first healthy quorum node to connect to quorum 440 andacquire a distributed lock is tentatively elected master according toApache ZooKeeper functionality. On confirmation with storage manager 340that the tentative master also has a lowest rank (see block 1602), thetentative master declares itself master also according to ApacheZooKeeper techniques. The declared master notifies storage manager 340of its master status, which is captured in management database 346. Asabove, communications with storage manager 340 and storage manageroperations are not provided by Apache Zookeeper.

Storage manager 340 maintains a timer measuring elapsed time since itpicked the first candidate master at block 1602. If after a pre-definedtimeout period no master has declared itself, storage manager 340selects another candidate by passing control back to block 1602. Afterthe master has been declared, control passes to block 1608.

At block 1608, the designated master monitor and proceeds to designateother heartbeat monitor nodes as worker nodes or observer nodes;configures and populates distributed file system 545 to all monitornodes; and sets “neighbor watch” processes or “adjacent watch”) amongquorum nodes (see, e.g., FIG. 9). Configuring distributed file system545 so that it comprises information useful for VM heartbeat monitoringis a feature of the illustrative embodiment. However, designating nodesas workers or observers, populating distributed file system 545 to othermonitor nodes, and setting watch processes is performed according toApache ZooKeeper techniques that are known in the art.

At block 1610, if the present master is newly established after a failedmaster node is detected (e.g., in/Failed_Masters), the present mastermonitor node notifies storage manager 340 to call failover on pendingmaster tasks. Accordingly, storage manager 340 assigns tasks that arepending from the failed master node to the newly declared master monitornode, according to the illustrative embodiment—thus managing a failoverof master tasks to the newly declared master.

At block 1612, a “neighbor” (or adjacent) quorum node that detects afailed master node (e.g., via watch) launches a master selection threadwithin itself. If the present “neighbor” (or adjacent) quorum node hasthe lowest rank among healthy quorum nodes (based on node's location asin block 1602) it becomes the new master monitor node and control passesback to block 1608; otherwise control passes to block 1604 for otherquorum nodes to vie for master role.

Eventually, a lowest-rank node in a still-operational source data centerwould become the new master monitor node. On the other hand, if thesource data center has catastrophically failed, the node scoring thelowest rank would likely be in the destination data center, which is thefailover destination.

FIG. 17 is a flow chart illustrating some salient details of block 1510in method 1500. In general, block 1510 is directed at the operationsperformed by a heartbeat monitor node (e.g., 410, 1310, 1410) in itsrole as master monitor node in quorum 440.

At block 1702, the master monitor node executes VM distribution logic(e.g., 608), resulting in a worker-to-VM mapping 6130. Master monitornode updates heartbeat monitoring distributed file system 545accordingly, e.g., updating target VM lists for each heartbeat monitornode (e.g., in data structure 802 of a data file 712). This operationgenerally occurs only when changes are detected (e.g., via watch), suchas at the initial system configuration, on the election of a new mastermonitor node, if a worker monitor node is down, when new production VMsare put in service, etc.

At block 1704, which is a decision point, the master monitor nodedetermines whether it received confirmation of failed target VM from aworker node, e.g., via watch in distributed file system 545 (see, e.g.,FIG. 9 and block 1910). Confirmation of a failed target VM is generallyrequired according to the illustrative embodiments, to ensure thatfailovers are called judiciously. Worker monitor nodes are responsiblefor confirming that target VMs are really in a failed state (see, e.g.,FIG. 19). If no such confirmation is received, the master monitor nodetakes no action, and control loops back to the start of block 1704. Whenconfirmation of a failed VM is received from a worker monitor node—usingthe watch system over distributed file system 545—control passes toblock 1706. Notably, the watch system ensures that a master monitor nodethat also operates as a worker node receives suitable notification fromthe watch process over the co-resident worker—see, e.g., FIG. 9.

At block 1706, the master monitor node takes the opportunity to furthercheck globally for other failed target VMs, e.g., via watch indistributed file system 545. Accordingly, the master monitor nodeassembles a list of all target VMs that are confirmed failed by theirrespective heartbeat monitor node.

At block 1708, having assembled a list of one or more target VMs thatare conformed failed, the master monitor node notifies storage manager340 to call failover (or failback) for all the one or more confirmedfailed target VMs. As noted elsewhere herein, upon receipt of thenotification from the master monitor node, storage manager (e.g., 340,1410) undertakes the management of failing over (or failback) of theconfirmed failed VMs 411, e.g., activating the replica VMs 421 atdestination data center 302, or at second cloud region 1303-2, etc.Managing VM failover by a storage manager such as 340, 1410 is wellknown in the art—after receiving notice from the master monitor nodeaccording to the illustrative embodiments.

FIG. 18 is a flow chart illustrating certain VM distribution rules 6122applied by VM distribution logic 608, when illustratively executed bythe master monitor node, e.g., at block 1702.

At block 1802, VM distribution logic 608 identifies a monitor nodedesignated as a worker (e.g., in source data center)—in round-robinfashion until each target VM has an assigned worker monitor node.

Block 1804 starts a loop: each target VM to be monitored execute blocks1806 through 1808 (as appropriate).

At block 1806, which is a decision point, VM distribution logic 608determines whether the present target VM is on the same VM network (asconfigured in the network adapter) AND host server as the identifiedworker monitor node. If yes, control passes to block 1818; otherwise,control passes to block 1808.

At block 1808, which is a decision point, VM distribution logic 608determines whether the present target VM is on the same VM network (asconfigured in the network adapter) as the identified worker monitornode. If yes, control passes to block 1818; otherwise, control passes toblock 1810.

At block 1810, which is a decision point, VM distribution logic 608determines whether the present target VM is hosted by same servercomputing device as the identified worker monitor node. If yes, controlpasses to block 1818; otherwise, control passes to block 1812.

At block 1812, which is a decision point, VM distribution logic 608determines whether the hop count from the identified worker monitor nodeto the present target VM is lower than from other monitor nodes (e.g.,less than 10 hops). If yes, control passes to block 1818; otherwise,control passes to block 1814.

At block 1814, VM distribution logic 608 determines whether the presenttarget VM is on the same subnet as defined in the IP address as theidentified worker monitor node. If yes, control passes to block 1818;otherwise, control passes to block 1816.

At block 1816, which is a decision point, VM distribution logic 608determines whether the round-trip ping latency from the identifiedworker monitor node to the present target VM is below an acceptabilitythreshold. The acceptability threshold depends on the implementednetwork topography and will be administered as a parameter in managementdatabase 346. If not, the identified worker monitor node is deemedunsuitable for the present target VM and control passes back to block1802 to identify another worker monitor node candidate; otherwise,control passes to block 1818.

At block 1818, VM distribution logic 608 (executed by the master monitornode) assigns the present target VM to the identified worker monitornode, e.g., filling in worker-to-VM mapping 6130. VM distribution logic608 (executed by the master monitor node) transmits the assignment tostorage manager 340, wherein the information is stored to managementdatabase 346.

FIG. 19 is flow chart illustrating certain salient operation in block1516 of method 1500. Block 1516 is generally directed at operationsperformed by worker monitor nodes, including ping monitoring of targetVMs and confirming whether target VMs have failed.

At block 1902, each worker monitor node (incl. a master node withassigned target VMs also operating as a worker node) performs blocks1904 through 1912.

At block 1904, the present worker monitor node identifies one or moretarget VM(s) (e.g., 411) assigned thereto by VM distribution logic 608,based on worker-to-VM mapping 6130 information reflected in datastructure 802 (see, e.g., FIG. 8).

At block 1906, the present worker monitor node executes ping monitoringlogic 610 relative to the assigned target VM(s) (e.g., 411). Thisincludes continuously sending customized packets to each target VM,waiting for a responsive packet, analyzing the response, if any, andprovisionally determining that the target VM has failed when no responseis received, followed by confirmation. More details are given in otherfigures herein (see, e.g., FIGS. 20, 20A).

At block 1908, which is a decision point, the present worker monitornode passes control back to block 1906 to continue pinging workingtarget VMs; if the present worker monitor node has confirmed that one ormore of its target VMs have failed, control passes to block 1910.Threads operate concurrently as appropriate to continue pinging workingVMs and to react to failed target VMs.

At block 1910, the present working monitor node updates data file 712 indistributed file system 545 at corresponding FS-node 722, e.g., updatingthe assigned VM target list and/or VMs confirmed failed in datastructure 802 (see, e.g., “All_VM List” and “Failed_VM List” in FIG. 8).The change to data file 712 will be detected by watch processes and thechange will be promulgated by the underlying Apache ZooKeeperinfrastructure 601. Accordingly, the master monitor node will becomeaware of the status change(s) of the failed VMs such as via watchprocess 922 (see, e.g., FIG. 9 and block 1704).

At block 1912, the present worker monitor node stops monitoring thetarget VM(s) confirmed failed the present worker monitor continues pingmonitoring of healthy target VMs.

FIG. 20 is a block diagram depicting an illustrative heartbeat packet2001 for pinging a target VM by a heartbeat monitor node designated as aworker node, e.g., 410, 1110, 1310, 1410.

The illustrative heartbeat packet 2001 that is transmitted to target VMsby each worker monitor node is a lightweight modified Internet ControlMessage Protocol (ICMP) Echo requests/reply message packet, preferably12 bytes in size. The illustrative embodiments leverage the ICMPprotocol structure to send/receive heartbeat packets.

Any machine (e.g., target VM 411) that receives an echo request such aspacket 2001 formulates an echo reply packet (not shown) and returns itto the original sender, e.g., worker monitor node. The echo request andassociated reply are used to test whether a target VM is reachable andresponding. Because both the request packet and reply packet travel inIP datagrams, successful receipt of a reply verifies that major piecesof the transport system work. First, IP software on the source computer(e.g., worker monitor node) must route the datagram. Second,intermediate routers between the source and target VM must be operatingand must route the datagram correctly. Third, the target VM must berunning (or at least respond to interrupts), and both ICMP and IPsoftware must be working. Finally, all routers along the return pathmust have correct routes.

ICMP protocol. TYPE in the ICMP message protocol represents echorequest/echo reply message. The echo request is type 8 when sender sendsto destination. When a target VM receives a type 8, it replies with atype 0. When the reply is sent, the source and destination addresses inthe packet switch places as well. After both of those changes, theCHECKSUM is recomputed, and the reply packet is sent. There is only oneCODE for both of these types, and is always set to 0. IDENTIFIER is setin the request packet 2001, and echoed back in the reply packet, to beable to keep different ping requests and replies together. IDENTIFIER isset as unique key of process ID. SEQUENCE NUMBER—The sequence number foreach host. DATA comprises optional content.

According to the illustrative embodiments the heartbeat packet 2001 isfilled with the following information. TYPE-8 for ICMP Echo and 0 forICMP Echo reply (1 byte). CODE always set to 0 (1 byte). CHECKSUM iscomputed for each packet (2 bytes). IDENTIFIER (2 bytes): the process IDlow (& operation of (Process ID, 0xFFFF flag)). SEQUENCE NUMBER (2bytes) generally starts from 1 and is incremented by one for eachpacket. DATA (4 bytes) comprises the packet number and the same packetnumber is validated in the echo reply packet, thus tracking of all theheartbeat packets sent.

Other implementations of the heartbeat packet 2001 and of correspondingecho reply packets are possible in alternative embodiments withoutlimitation.

FIG. 20A is a flow chart illustrating certain salient operation in block1906 of method 1500. Block 1906 is generally directed at ping monitoringoperations, including ping monitoring logic 610 executed by workermonitor nodes. The illustrative heartbeat packets 2001 transmitted byworker monitor nodes towards their target VMs are described in moredetail in FIG. 20.

Illustratively, ping monitoring logic 610 comprises a number offeatures, executed by corresponding threads—illustratively five threadsrunning in parallel to accomplish the monitoring of target VMs: SendPacket Thread, Process Packet Thread, Receive Packet Thread, ManagePacket Thread and Back End Thread. Additional details are given in U.S.Provisional Patent Application Ser. No. 62/402,269, filed on Sep. 30,2016 and entitled “Heartbeat Monitoring of Virtual Machines forInitiating Failover Operations in a Data Storage Management System,”which is incorporated by reference herein.

Illustratively, ping monitoring logic 610 uses non-blocking sockets tosend/receive heartbeat packets (e.g., 2001) continuously andconcurrently to optimize packet distribution across VMs efficiently.Advantageously, shorter wait times are achieved when there is a networkpartition and VMs are not responsive. Statistics on packets aremaintained in a synchronized map (e.g., Ping Stats map—not shown here).All the above threads constantly communicate with the synchronized mapto update/get/remove packet entries therein. There are also,illustratively, three separate event queues (not shown here) forcommunication between threads: Send Queue—send VM packets constantlythrough send ( )non-blocking socket; Receive Queue—receives echo replypackets continuously from the VMs; and Wait Queue—puts any maintenanceVMs in wait state.

Heartbeat packets (e.g., 2001) are filled in the Send Queue by theManage Packet Thread. In a first round, the first heartbeat packet foreach target VM are sent. In the next iteration, the second heartbeatpacket for each target VM are sent. This iterative process repeats untila last (preferably tenth) round of transmissions is completed, withoutlimitation. By using this technique, pings are distributed to all targetVMs with reduced wait times and not ignoring any target VMs. The pingmonitoring threads are described in more detail next.

Send Packet Thread runs continuously and picks up the packets to be sentto target VMs from the Send Queue; constructs heartbeat packets (e.g.,2001) and sends heartbeat packets continuously through send 0non-blocking socket. It also updates packet statistics in thesynchronized map. Each heartbeat packet sent out via the non-blockingsocket is tracked in the synchronized map.

Process Packet Thread runs continuously and constantly listens to therecv ( ) non-blocking socket forming an event loop. Whenever aresponsive echo reply packet arrives to the socket, this thread picks itup and puts in the Receive Queue. If the socket is suddenly closed, thisthread re-opens the non-blocking socket to continue monitoring.

Receive Packet Thread runs continuously and picks up echo reply packetsput in the Receive Queue. It unpacks each echo reply packet andvalidates the receive times of echo reply packets and updates thesynchronized map. If the echo reply packet arrives within a pre-definedmaximum packet timeout period, then the packet's entries in thesynchronized map are deleted; otherwise (arrival past the timeoutperiod) the packet's entries are updated in the synchronized map for theManage Packet Thread to analyze.

Manage Packets Thread runs continuously. This thread initially receivesthe worker monitor node's list of target VMs. Manage Packets Threadfills the Send Queue as described above. Manage Packets Thread inbetween each fill also analyzes by using Packet Analyzing Logic,described in more detail below.

Back End Thread runs in the background to refrain from heartbeatmonitoring certain VMs if a maintenance timeout is set for therespective target VM (e.g., set by a user)—so-called “maintenance VMs.”The Back End Thread temporarily pauses the monitoring of maintenance VMsby placing them into a wait queue. A timer is started for eachmaintenance VM and when the timer expires, these VMs are no longerconsidered to be under maintenance and are put back to the main queuefor heartbeat monitoring. The parent Back End Thread will create childthreads for each maintenance VM and starts a corresponding timer foreach one. The Back End Thread is useful when a user wants to refrainfrom monitoring target VMs while performing maintenance thereupon.

Packet Analyzing Logic. Entries in the synchronized map illustrativelycomprise: destination VM IP address, packet number, start time, endtime, and maximum timeout for each heartbeat packet (e.g., 2001). Theseare filled in by the Send Packet Thread. Whenever the echo reply packetarrives after the timeout period or no echo reply packet is received atall, the illustrative Receive Packet Thread does not delete the packet'sentries in the synchronized map. The illustrative Manage Packets Threadanalyzes the packet by computing the number of rows in the synchronizedmap divided by the actual number of heartbeat packets sent to the targetVM. If this ratio is less than a predefined packet loss threshold thenthe VM is considered to be alive (at least from the perspective ofheartbeat monitoring logic). Example: (number of packet rows for eachVM)/(number of heartbeat packets sent to theVM)<Max_packet_loss_threshold

VM is alive.

Illustratively, the Max_packet_loss_threshold is initialized to 75%,thus allowing for up to 75% packet loss for the given target VM. If thepacket loss percentage exceeds this threshold, the ping monitoring logicassumes that the target VM is not reachable and the Manage PacketsThread confirms the given VM's status by illustratively querying the VMdata center and/or the VM's host/server (e.g., 401) to check the VM'spower state. If the VM power state is confirmed to be offline then thetarget VM is considered to be down. The Manage Packets Thread updatesthis down state to the worker monitor node (e.g., by updating datastructure 802 in the /Worker FS-node of distributed file system 545); inturn, this change is picked up by the watch process 922 of the/MasterFS-node, and cause the master monitor node to notify storage manager 340to call failover of the given VM (e.g., block 1708). On the other hand,if the query response from the VM data center and/or VM host/serverindicates that the given target VM is online, then the Manage PacketsThread treats the unresponsiveness as a false alarm and heartbeatmonitoring continues.

The flow chart in the present figure comprises the following operations,without limitation. Since the disclosed threads run on an ongoing basisand concurrently in any given worker monitor node, the operations shownin the flow chart are not to be taken as exclusively sequential and areto be read in light of the thread descriptions given in theabovementioned paragraphs, and in further light of the ping monitoringsystem architecture depicted and described in U.S. Provisional PatentApplication Ser. No. 62/402,269, filed on Sep. 30, 2016 and entitled“Heartbeat Monitoring of Virtual Machines for Initiating FailoverOperations in a Data Storage Management System,” which is incorporatedby reference herein.

At block 2022, groups of heartbeat packets (e.g., groups of ten packets2001) are transmitted to each of the monitor node's target VMs (e.g.,411), e.g., using the Manage Packets Thread, and the Send Packet Thread.(e.g., {target1, packet1}, {target2, packet1}, {target3, packet1} . . .{target1, packet10}, {target2, packet10}, and {target3, packet10}).

At block 2024, ping monitoring logic 610 waits for and processesresponsive echo reply packets arriving from target VMs in response tothe groups of packets transmitted thereto at block 2022, e.g., using theProcess Packet Thread, and the Receive Packet Thread.

At block 2026, which is a decision point, the Packet Analyzing Logicdetermines whether one or more (as many as ten, illustratively)responsive echo reply packets were received from a given target VMwithin a predefined timeout interval, e.g., five seconds. If so, thetarget VM is deemed to be operational and control passes to block 2030to compute the response rate. Otherwise, when no responses are receivedfrom a given target VM, control passes to block 2028 to enable retries.

At block 2028, a group of heartbeat packets (e.g., ten packets 2001) isre-sent to the non-responsive VM to begin a process of confirmingwhether the given VM is alive or down. The number of re-sends is up tothe implementers and the invention is not so limited. Illustratively,two re-sends are used, each followed by the pre-defined timeout interval(e.g., five seconds). Thus, control passes back to block 2022.

At block 2030, which is a decision point, the illustrative PacketAnalyzing Logic determines whether as to a given target VM the packetresponse (echo) loss rate exceeds a predefined packet loss thresholdconsidered to be acceptable (e.g., 75%). The illustrative threshold thusallows for substantial (e.g., 75%) packet loss in responding to VMheartbeat packets, resulting from a number of scenarios, such asheartbeat packets 2001 never reaching the target VM, target VMs beingslow to respond, echo packets getting lost, or the target VM has failedaltogether. If the packet loss rate falls below the predefined lossthreshold (e.g., 50% loss rate <75% threshold), then the target VM isdeemed to be operational and (at least superficially) healthy from theperspective of heartbeat monitoring, and therefore control passes backto block 2022 for continued heartbeat monitoring. Otherwise, when thepacket loss rate exceed the generous acceptability threshold (e.g., 90%loss rate >75% threshold), further confirmatory action is needed andcontrol passes to block 2032. The illustrative synchronization map ismaintained here by the illustrative Packet Analyzing Logic.

At block 2032, ping monitoring logic 610 seeks to confirm a given targetVM's power status by directly querying the given VM's infrastructure,e.g., VM data center and/or VM host/server (e.g., 401). Queries to andstatus responses from VM infrastructure are well known in the art, e.g.,querying a hypervisor.

At block 2034, which is a decision point, ping monitoring logic 610,e.g., using Back End Thread, analyzes response(s) received from the VMinfrastructure to determine whether the given VM is currently suspendedfor maintenance, typically suspended by user intervention. If the givenVM is reportedly suspended for maintenance, control passes to block2036. If the given VM is reported down (offline, dead, non-operational),the Back End Logic classifies the VM as failed and control passes toblock 2038. Situations arise when the VM infrastructure reports thegiven VM to be alive (online, operational) despite the unacceptable(above-threshold) packet loss rate as determined at block 2030.Accordingly, the illustrative embodiments treat the VM as alive andcontrol passes back to block 2022 for continued heartbeat monitoring. Inalternative embodiments, the given VM is treated as unhealthy based onthe excessive echo packet loss rate and control passes to block 2038.

At block 2036, when the given VM is reportedly suspended formaintenance, Back End Logic sets a timer to await the end ofmaintenance. Meanwhile, heartbeat monitoring (e.g., blocks 2022, 2024,etc.) is suspended and upon timer expiration control passes back toblock 2034. According to the illustrative embodiments these timers maybe renewed.

At block 2038, when the given VM is confirmed failed (or treated assuch), control passes from block 1906 to block 1908 for confirming theVM failure to the master monitor node (so that it can notify storagemanager 340 to call failover for the failed VM). When a worker nodeconfirms a VM as failed (or treats it as such), the worker node updatesits entry in data structure 802 (Failed_VM list), which change isdetected by the master monitor node using a watch process 922.

FIG. 21 is a flow chart illustrating certain salient operations in block1518 of method 1500. Block 1518 is generally directed at operationsperformed by the master monitor node when a worker monitor node hasfailed—so-called backstop operations.

At block 2102, the master monitor node detects a failed worker monitornode, e.g., via watch process 924 over the given worker node's /Is_aliveflag 724 in distributed file system 545. See also FIG. 9.

At block 2104, the master monitor node further makes a global check forother failed worker monitor nodes, e.g., via watch process 924 over/Is_alive flags 724 in distributed file system 545.

At block 2106, the master monitor node locally updatesthe/Failed_Workers 706 data structure in its local instance ofdistributed file system 545 to indicate which of the worker monitornodes are in a failed state. After this, control passes to block 1702(within block 1510) for executing VM distribution logic to re-distributetarget VMs to operational worker nodes and away from the non-operationalworker node(s) detected above.

According to the illustrative embodiments, VMs that operate as workernodes are not monitored, in order to reserve computational resources formonitoring important production VMs, but the invention is not solimited. Therefore, in some alternative embodiments, the master monitornode could be configured to monitor worker nodes.

The enumerated functionality above is presented without limitation, andit will be understood by those having ordinary skill in the art, afterreading the present disclosure, that substantial additionalfunctionality is enabled by the disclosed architecture herein. In regardto the figures included and described herein, other embodiments arepossible within the scope of the present invention, such that theabove-recited components, steps, blocks, operations, messages, requests,queries, and/or instructions are differently arranged, sequenced,sub-divided, organized, and/or combined. In some embodiments, adifferent component may initiate or execute a given operation.

Example Embodiments

According to an illustrative embodiment of the present invention, amethod comprising: receiving, by a first data agent configured as amaster monitor node in a data storage management system, a first noticeof a first virtual machine that is confirmed failed, wherein the firstdata agent is in communication with a storage manager that managesstorage management operations in the data storage management system, andwherein the first data agent executes on one of (i) a nonvirtualizedcomputing device comprising one or more processors and computer memory,and (ii) a first virtual machine executing on a computing devicecomprising one or more processors and computer memory and executing ahypervisor; based on the first notice, checking, by the master monitornode, whether other virtual machines are also confirmed failed; andnotifying, by the master monitor, the storage manager to call failoverfor the first virtual machine and any of the other virtual machines thatare also confirmed failed based on the checking.

The above-recited method further comprising: managing, by the storagemanager, a failover operation for the first virtual machine, wherein thefailover operation activates a second virtual machine located in asecond data center to operate in place of the failed first virtualmachine located in a first data center. The above-recited method furthercomprising: managing, by the storage manager, a failover operation forthe first virtual machine, wherein the failover operation activates asecond virtual machine located in a second region of a cloud serviceprovider to operate in place of the failed first virtual machine locatedin a first region of a cloud service provider. The above-recited methodfurther comprising: managing, by the storage manager, a failoveroperation for the first virtual machine, wherein the failover operationactivates a second virtual machine to operate in place of the failedfirst virtual machine, wherein prior to the failover operation, thestorage manager managed a replication operation of the first virtualmachine to the second virtual machine. The above-recited method furthercomprising: managing, by the storage manager, a failover operation forthe first virtual machine, wherein the failover operation activates asecond virtual machine to operate in place of the failed first virtualmachine, wherein prior to the failover operation, the storage managermanaged a live synchronization operation of the first virtual machine tothe second virtual machine. The above-recited method wherein the firstnotice of the first virtual machine being confirmed failed is receivedby the master monitor node from a second data agent configured as aworker monitor node in the data storage management system, and whereinthe second data agent executes on one of (i) a nonvirtualized computingdevice comprising one or more processors and computer memory, and (ii) afirst virtual machine executing on a computing device comprising one ormore processors and computer memory and executing a hypervisor. Theabove-recited method wherein the first data agent is also configured tooperate as a first worker monitor node which performs heartbeatmonitoring of the first virtual machine and generates the first noticeof the first virtual machine being confirmed failed.

According to another illustrative embodiment, a computer-readablemedium, excluding transitory propagating signals, storing instructionsthat, when executed by a computing device, cause the computing device toperform operations comprising: receiving, by a first data agentconfigured as a master monitor node, a first notice of a first virtualmachine that is confirmed failed, wherein the first data agent is incommunication with a storage manager that manages storage managementoperations in a data storage management system, and wherein the firstdata agent executes on the computing device comprising one of: (i) oneor more processors and computer memory, and (ii) a first virtual machinehosted by a hypervisor executing on one or more processors and computermemory; based on the first notice, checking, by the master monitor node,whether other virtual machines are also confirmed failed; and notifying,by the master monitor, the storage manager to call failover for thefirst virtual machine and any of the other virtual machines that arealso confirmed failed based on the checking.

The above-recited computer-readable medium further comprising: managing,by the storage manager, a failover operation for the first virtualmachine, wherein the failover operation activates a second virtualmachine located in a second data center to operate in place of thefailed first virtual machine located in a first data center. Theabove-recited computer-readable medium further comprising: managing, bythe storage manager, a failover operation for the first virtual machine,wherein the failover operation activates a second virtual machinelocated in a second region of a cloud service provider to operate inplace of the failed first virtual machine located in a first region of acloud service provider. The above-recited computer-readable mediumfurther comprising: managing, by the storage manager, a failoveroperation for the first virtual machine, wherein the failover operationactivates a second virtual machine to operate in place of the failedfirst virtual machine, wherein prior to the failover operation, thestorage manager managed a replication operation of the first virtualmachine to the second virtual machine. The above-recitedcomputer-readable medium further comprising: managing, by the storagemanager, a failover operation for the first virtual machine, wherein thefailover operation activates a second virtual machine to operate inplace of the failed first virtual machine, wherein prior to the failoveroperation, the storage manager managed a live synchronization operationof the first virtual machine to the second virtual machine. Theabove-recited computer-readable medium wherein the first notice of thefirst virtual machine being confirmed failed is received by the mastermonitor node from a second data agent configured as a worker monitornode in the data storage management system, and wherein the second dataagent executes on one of (i) a nonvirtualized computing devicecomprising one or more processors and computer memory, and (ii) a firstvirtual machine executing on a computing device comprising one or moreprocessors and computer memory and executing a hypervisor. Theabove-recited computer-readable medium wherein the first data agent isalso configured to operate as a first worker monitor node which performsheartbeat monitoring of the first virtual machine and generates thefirst notice of the first virtual machine being confirmed failed.

According to yet another illustrative embodiment, a system for assigningvirtual machines as targets for heartbeat monitoring by heartbeatmonitor nodes in a data storage management system, the systemcomprising: a first data agent that executes on a computing devicecomprising one of: (i) one or more processors and computer memory, and(ii) a first virtual machine hosted by a hypervisor executing on one ormore processors and computer memory, wherein the first data agent isconfigured to operate as a master monitor node in the data storagemanagement system, and wherein the first data agent is in communicationwith a storage manager that manages storage management operations in thedata storage management system; and wherein the master monitor node isconfigured to: receive a first notice of a first virtual machine that isconfirmed failed, based on the first notice, check whether other virtualmachines are also confirmed failed, and notify the storage manager tocall failover for the first virtual machine and any of the other virtualmachines that are also confirmed failed based on the check operation.

The above-recited system further comprising: managing, by the storagemanager, a failover operation for the first virtual machine, wherein thefailover operation activates a second virtual machine located in asecond data center to operate in place of the failed first virtualmachine located in a first data center. The above-recited system furthercomprising: managing, by the storage manager, a failover operation forthe first virtual machine, wherein the failover operation activates asecond virtual machine located in a second region of a cloud serviceprovider to operate in place of the failed first virtual machine locatedin a first region of a cloud service provider. The above-recited systemfurther comprising: managing, by the storage manager, a failoveroperation for the first virtual machine, wherein the failover operationactivates a second virtual machine to operate in place of the failedfirst virtual machine, wherein prior to the failover operation, thestorage manager managed a replication operation of the first virtualmachine to the second virtual machine. The above-recited system furthercomprising: managing, by the storage manager, a failover operation forthe first virtual machine, wherein the failover operation activates asecond virtual machine to operate in place of the failed first virtualmachine, wherein prior to the failover operation, the storage managermanaged a live synchronization operation of the first virtual machine tothe second virtual machine. The above-recited system wherein the firstnotice of the first virtual machine being confirmed failed is receivedby the master monitor node from a second data agent configured as aworker monitor node in the data storage management system, and whereinthe second data agent executes on one of (i) a nonvirtualized computingdevice comprising one or more processors and computer memory, and (ii) afirst virtual machine executing on a computing device comprising one ormore processors and computer memory and executing a hypervisor. Theabove-recited system wherein the first data agent is also configured tooperate as a first worker monitor node which performs heartbeatmonitoring of the first virtual machine and generates the first noticeof the first virtual machine being confirmed failed.

According to another example embodiment a method comprising: configuringa first data agent as a master monitor node in a data storage managementsystem, wherein the first data agent is in communication with a storagemanager that manages storage management operations in the data storagemanagement system, and wherein the first data agent executes on one of(i) a nonvirtualized computing device comprising one or more processorsand computer memory, and (ii) a first virtual machine hosted by ahypervisor executing on a computing device comprising one or moreprocessors and computer memory, and wherein the master monitor nodecomprises an instance of a distributed file system; configuring a seconddata agent as a first worker monitor node in a data storage managementsystem, wherein the first worker monitor node performs heartbeatmonitoring of a plurality of virtual machines assigned thereto by themaster monitor node, wherein the second data agent executes on one of(i) a nonvirtualized computing device comprising one or more processorsand computer memory, and (ii) a second virtual machine hosted by ahypervisor executing on a computing device comprising one or moreprocessors and computer memory, and wherein the first worker monitornode comprises an instance of the distributed file system; detecting, bythe master monitor node, based on a change in the distributed filesystem, that the first worker monitor node has failed; querying one of:(a) the nonvirtualized computing device, (b) the hypervisor that hoststhe second virtual machine, and (c) a controller of a virtual machinedata center comprising the second virtual machine about an operationalstatus of the first worker monitor node; and if, responsive to thequerying, the operational status of the first worker monitor node isreported to be failed, (I) updating a list of failed worker monitornodes in the distributed file system, and (II) re-assigning, by themaster monitor node, the plurality of virtual machines assigned to thefailed first worker monitor node to a second worker monitor node in thedata storage management system.

The above-recited method wherein after the re-assigning, the secondworker monitor node performs heartbeat monitoring of the plurality ofvirtual machines assigned thereto by the master monitor node. Theabove-recited method wherein a third data agent is configured as thesecond worker monitor node, and wherein the third data agent executes onone of (i) a nonvirtualized computing device comprising one or moreprocessors and computer memory, and (ii) a third virtual machine hostedby a hypervisor executing on a computing device comprising one or moreprocessors and computer memory, and wherein the second worker monitornode comprises an instance of the distributed file system. Theabove-recited method wherein a third data agent is configured as thesecond worker monitor node, and wherein the third data agent executes onone of (i) a nonvirtualized computing device comprising one or moreprocessors and computer memory, and (ii) a third virtual machine hostedby a hypervisor executing on a computing device comprising one or moreprocessors and computer memory, and wherein the second worker monitornode comprises an instance of the distributed file system; anddetecting, by the second worker monitor node, based on a change in thedistributed file system, that the plurality of virtual machines havebeen re-assigned thereto. The above-recited method further comprising:if, responsive to the querying, the operational status of the firstworker monitor node is reported to be failed, before the re-assigning ofthe plurality of virtual machines, (Ill) determining whether any of theplurality of virtual machines are also confirmed failed in the datastorage management system, and (IV) notifying the storage manager tocall failover for any of the plurality of virtual machines confirmedfailed. The above-recited method further comprising: managing, by thestorage manager, a respective failover operation for any of theplurality of virtual machines confirmed failed, wherein the respectivefailover operation activates a corresponding second virtual machine tooperate in place of a failed first virtual machine. The above-recitedmethod further comprising: managing, by the storage manager, arespective failover operation for any of the plurality of virtualmachines confirmed failed, wherein the respective failover operationactivates a corresponding second virtual machine to operate in place ofa failed first virtual machine, wherein prior to the failover operation,the storage manager managed a replication operation of the first virtualmachine to the second virtual machine. The above-recited method furthercomprising: managing, by the storage manager, a respective failoveroperation for any of the plurality of virtual machines confirmed failed,wherein the respective failover operation activates a correspondingsecond virtual machine to operate in place of a failed first virtualmachine, wherein prior to the failover operation, the storage managermanaged a live synchronization operation of the first virtual machine tothe second virtual machine.

According to another example embodiment, a computer-readable medium,excluding transitory propagating signals, storing instructions that,when executed by a computing device, cause the computing device toperform operations comprising: configuring a first data agent as amaster monitor node in a data storage management system, wherein thefirst data agent is in communication with a storage manager that managesstorage management operations in the data storage management system, andwherein the first data agent executes on the computing device comprisingone of: (i) one or more processors and computer memory, and (ii) a firstvirtual machine hosted by a hypervisor executing on one or moreprocessors and computer memory, and wherein the master monitor nodecomprises an instance of a distributed file system; configuring a seconddata agent as a first worker monitor node in the data storage managementsystem, wherein the first worker monitor node performs heartbeatmonitoring of a plurality of virtual machines assigned thereto by themaster monitor node, wherein the second data agent executes on one of(i) a nonvirtualized computing device comprising one or more processorsand computer memory, and (ii) a second virtual machine hosted by ahypervisor executing on a computing device comprising one or moreprocessors and computer memory, and wherein the first worker monitornode comprises an instance of the distributed file system; detecting, bythe master monitor node, based on a change in the distributed filesystem, that the first worker monitor node has failed; querying one of:(a) the nonvirtualized computing device, (b) the hypervisor that hoststhe second virtual machine, and (c) a controller of a virtual machinedata center comprising the second virtual machine about an operationalstatus of the first worker monitor node; and if, responsive to thequerying, the operational status of the first worker monitor node isreported to be failed, (I) updating a list of failed worker monitornodes in the distributed file system, and (II) re-assigning, by themaster monitor node, the plurality of virtual machines assigned to thefailed first worker monitor node to a second worker monitor node in thedata storage management system.

The above-recited computer-readable medium wherein after there-assigning, the second worker monitor node performs heartbeatmonitoring of the plurality of virtual machines assigned thereto by themaster monitor node. The above-recited computer-readable medium whereina third data agent is configured as the second worker monitor node, andwherein the third data agent executes on one of (i) a nonvirtualizedcomputing device comprising one or more processors and computer memory,and (ii) a third virtual machine hosted by a hypervisor executing on acomputing device comprising one or more processors and computer memory,and wherein the second worker monitor node comprises an instance of thedistributed file system. The above-recited computer-readable mediumwherein a third data agent is configured as the second worker monitornode, and wherein the third data agent executes on one of (i) anonvirtualized computing device comprising one or more processors andcomputer memory, and (ii) a third virtual machine hosted by a hypervisorexecuting on a computing device comprising one or more processors andcomputer memory, and wherein the second worker monitor node comprises aninstance of the distributed file system; and detecting, by the secondworker monitor node, based on a change in the distributed file system,that the plurality of virtual machines have been re-assigned thereto.The above-recited computer-readable medium further comprising: if,responsive to the querying, the operational status of the first workermonitor node is reported to be failed, before the re-assigning of theplurality of virtual machines, (Ill) determining whether any of theplurality of virtual machines are also confirmed failed in the datastorage management system, and (IV) notifying the storage manager tocall failover for any of the plurality of virtual machines confirmedfailed. The above-recited computer-readable medium further comprising:managing, by the storage manager, a respective failover operation forany of the plurality of virtual machines confirmed failed, wherein therespective failover operation activates a corresponding second virtualmachine to operate in place of a failed first virtual machine. Theabove-recited computer-readable medium further comprising: managing, bythe storage manager, a respective failover operation for any of theplurality of virtual machines confirmed failed, wherein the respectivefailover operation activates a corresponding second virtual machine tooperate in place of a failed first virtual machine, wherein prior to thefailover operation, the storage manager managed a replication operationof the first virtual machine to the second virtual machine. Theabove-recited computer-readable medium further comprising: managing, bythe storage manager, a respective failover operation for any of theplurality of virtual machines confirmed failed, wherein the respectivefailover operation activates a corresponding second virtual machine tooperate in place of a failed first virtual machine, wherein prior to thefailover operation, the storage manager managed a live synchronizationoperation of the first virtual machine to the second virtual machine.

According to yet another example embodiment, a system for assigningvirtual machines as targets for heartbeat monitoring by heartbeatmonitor nodes in a data storage management system, the systemcomprising: a first data agent that executes on a computing devicecomprising one of: (i) one or more processors and computer memory, and(ii) a first virtual machine hosted by a hypervisor executing on one ormore processors and computer memory, wherein the first data agent isconfigured to operate as a master monitor node in the data storagemanagement system, and wherein the first data agent is in communicationwith a storage manager that manages storage management operations in thedata storage management system; and wherein the master monitor nodecomprises an instance of a distributed file system; a second data agentthat executes on a computing device comprising one of: (i) one or moreprocessors and computer memory, and (ii) a first virtual machine hostedby a hypervisor executing on one or more processors and computer memory,wherein the second data agent is configured to operate as a first workermonitor node in the data storage management system, and wherein thesecond data agent is in communication with a storage manager thatmanages storage management operations in the data storage managementsystem; wherein the first worker monitor node comprises an instance ofthe distributed file system; wherein the master monitor node isconfigured to: detect, based on a change in the distributed file system,that the first worker monitor node has failed, query one of: (a) thenonvirtualized computing device, (b) the hypervisor that hosts thesecond virtual machine, and (c) a controller of a virtual machine datacenter comprising the second virtual machine about an operational statusof the first worker monitor node, and if, responsive to the querying,the operational status of the first worker monitor node is reported tobe failed, (I) updating a list of failed worker monitor nodes in thedistributed file system, and (II) re-assigning, by the master monitornode, the plurality of virtual machines assigned to the failed firstworker monitor node to a second worker monitor node in the data storagemanagement system.

The above-recited system wherein after the re-assigning, the secondworker monitor node performs heartbeat monitoring of the plurality ofvirtual machines assigned thereto by the master monitor node. Theabove-recited system wherein a third data agent is configured as thesecond worker monitor node, and wherein the third data agent executes onone of (i) a nonvirtualized computing device comprising one or moreprocessors and computer memory, and (ii) a third virtual machine hostedby a hypervisor executing on a computing device comprising one or moreprocessors and computer memory, and wherein the second worker monitornode comprises an instance of the distributed file system. Theabove-recited system wherein a third data agent is configured as thesecond worker monitor node, and wherein the third data agent executes onone of (i) a nonvirtualized computing device comprising one or moreprocessors and computer memory, and (ii) a third virtual machine hostedby a hypervisor executing on a computing device comprising one or moreprocessors and computer memory, and wherein the second worker monitornode comprises an instance of the distributed file system; anddetecting, by the second worker monitor node, based on a change in thedistributed file system, that the plurality of virtual machines havebeen re-assigned thereto. The above-recited system further comprising:if, responsive to the querying, the operational status of the firstworker monitor node is reported to be failed, before the re-assigning ofthe plurality of virtual machines, (Ill) determining whether any of theplurality of virtual machines are also confirmed failed in the datastorage management system, and (IV) notifying the storage manager tocall failover for any of the plurality of virtual machines confirmedfailed. The above-recited system further comprising: managing, by thestorage manager, a respective failover operation for any of theplurality of virtual machines confirmed failed, wherein the respectivefailover operation activates a corresponding second virtual machine tooperate in place of a failed first virtual machine. The above-recitedsystem further comprising: managing, by the storage manager, arespective failover operation for any of the plurality of virtualmachines confirmed failed, wherein the respective failover operationactivates a corresponding second virtual machine to operate in place ofa failed first virtual machine, wherein prior to the failover operation,the storage manager managed a replication operation of the first virtualmachine to the second virtual machine. The above-recited system furthercomprising: managing, by the storage manager, a respective failoveroperation for any of the plurality of virtual machines confirmed failed,wherein the respective failover operation activates a correspondingsecond virtual machine to operate in place of a failed first virtualmachine, wherein prior to the failover operation, the storage managermanaged a live synchronization operation of the first virtual machine tothe second virtual machine.

Another illustrative embodiment comprises a method for heartbeatmonitoring virtual machines in a data storage management system, themethod comprising: configuring a first data agent to operate as a firstworker monitor node, wherein the first data agent executes on one of:(i) a computing device comprising one or more processors and computermemory, and (ii) a first virtual machine hosted by a hypervisorexecuting on a computing device comprising one or more processors andcomputer memory; transmitting, from the first worker monitor node, aplurality of data packets to a second virtual machine hosted by a firsthypervisor executing on a computing device comprising one or moreprocessors and computer memory, wherein the second virtual machine isone of a plurality of virtual machines which are assigned to the firstworker monitor node for heartbeat monitoring; when the first workermonitor node determines that a rate of responses to the plurality ofdata packets falls below a predefined threshold, querying one of: (a)the first hypervisor, and (b) a controller of a virtual machine datacenter comprising the first hypervisor about an operational status ofthe second virtual machine; if, responsive to the querying, theoperational status of the second virtual machine is reported to befailed, (a) refraining from further transmitting of data packets by thefirst worker monitor node to the second virtual machine.

The above-recited method wherein if, responsive to the querying, theoperational status of the second virtual machine is reported to befailed, (b) reporting to a master monitor node that the second virtualmachine has been confirmed failed, wherein the reporting comprisesupdating, by the first worker monitor node, a data structure in adistributed file system having an instance on the first worker monitornode and on the master monitor node. The above-recited method furthercomprising: if, responsive to the querying, the operational status ofthe second virtual machine is reported to be active, resuming thetransmitting of data packets by the first worker monitor node to thesecond virtual machine. The above-recited method further comprising: if,responsive to the querying, the operational status of the second virtualmachine is reported to be undergoing maintenance, (i) suspending for atime period the transmitting of data packets by the first worker monitornode to the second virtual machine, and (ii) after the time periodexpires, querying again about the operational status of the secondvirtual machine. The above-recited method wherein a second data agent isconfigured to operate as a master monitor node and executes on one of(i) a computing device comprising one or more processors and computermemory, and (ii) a third virtual machine hosted by a hypervisorexecuting on a computing device comprising one or more processors andcomputer memory; and wherein the master monitor node notifies a storagemanager that the second virtual machine has been confirmed failed; andwherein the storage manager manages storage management operations in thedata storage management system. The above-recited method furthercomprising: managing, by the storage manager, a failover operation forthe second virtual machine, wherein a fourth virtual machine isactivated to operate in place of the failed second virtual machine. Theabove-recited method further comprising: managing, by the storagemanager, a failover operation for the second virtual machine, wherein afourth virtual machine is activated to operate in place of the failedsecond virtual machine; and wherein prior to the failover operation, thestorage manager managed a replication operation of the second virtualmachine to the fourth virtual machine. The above-recited method furthercomprising: managing, by the storage manager, a failover operation forthe second virtual machine, wherein a fourth virtual machine isactivated to operate in place of the failed second virtual machine; andwherein prior to the failover operation, the storage manager managed alive synchronization operation of the second virtual machine to thefourth virtual machine. The above-recited method wherein the first dataagent is further configured to operate as a master monitor node; andwherein the master monitor node notifies a storage manager that thesecond virtual machine has been confirmed failed, and wherein thestorage manager manages storage management operations in the datastorage management system. The above-recited method wherein the firstworker monitor node transmits a first respective data packet to each ofthe plurality of virtual machines which are assigned to the first workermonitor node for heartbeat monitoring before transmitting a secondrespective data packet to each of the plurality of virtual machines. Theabove-recited method further comprising: for a given data packet fromamong the plurality of data packets transmitted to the second virtualmachine, waiting by the first worker monitor node for a responsive datapacket to arrive within a predefined timeout interval; if the responsivedata packet does not arrive within the predefined timeout interval,re-transmitting, by the first worker monitor node, the given data packetto the second virtual machine, wherein the re-transmitting is limited toa predefined count. The above-recited method wherein the rate ofresponses to the plurality of data packets includes the re-transmittingof the given data packet. The above-recited method wherein the firstworker monitor node executes an instance of Apache ZooKeeper server andclient services and is part of a quorum that also includes the mastermonitor node. The above-recited method wherein the first worker monitornode executes an instance of Apache ZooKeeper client services; whereinthe master monitor node is part of a quorum of monitor nodes; andwherein the first worker monitor node is not part of the quorum.

Yet another illustrative embodiment comprises a computer-readablemedium, excluding transitory propagating signals, storing instructionsthat, when executed by a computing device, cause the computing device toperform operations comprising: transmitting, from a first worker monitornode, a plurality of data packets to a second virtual machine hosted bya first hypervisor executing on a computing device comprising one ormore processors and computer memory, wherein the second virtual machineis one of a plurality of virtual machines which are assigned to thefirst worker monitor node for heartbeat monitoring, wherein a first dataagent is configured to operate as the first worker monitor node, whereinthe first data agent executes on the computing device, which comprisesone of: (i) one or more processors and computer memory, and (ii) a firstvirtual machine hosted by a hypervisor executing on the computing devicehaving one or more processors and computer memory; when the first workermonitor node determines that a rate of responses to the plurality ofdata packets falls below a predefined threshold, querying one of: (a)the first hypervisor, and (b) a controller of a virtual machine datacenter comprising the first hypervisor about an operational status ofthe second virtual machine; and if, responsive to the querying, theoperational status of the second virtual machine is reported to befailed, (a) refraining from further transmitting of data packets by thefirst worker monitor node to the second virtual machine.

The above-recited computer-readable medium wherein if, responsive to thequerying, the operational status of the second virtual machine isreported to be failed, (b) reporting to a master monitor node that thesecond virtual machine has been confirmed failed, wherein the reportingcomprises updating, by the first worker monitor node, a data structurein a distributed file system having an instance on the first workermonitor node and on the master monitor node. The above-recitedcomputer-readable medium further comprising: if, responsive to thequerying, the operational status of the second virtual machine isreported to be active, resuming the transmitting of data packets by thefirst worker monitor node to the second virtual machine. Theabove-recited computer-readable medium further comprising: if,responsive to the querying, the operational status of the second virtualmachine is reported to be undergoing maintenance, (i) suspending for atime period the transmitting of data packets by the first worker monitornode to the second virtual machine, and (ii) after the time periodexpires, querying again about the operational status of the secondvirtual machine. The above-recited computer-readable medium wherein asecond data agent is configured to operate as a master monitor node andexecutes on one of (i) a computing device comprising one or moreprocessors and computer memory, and (ii) a third virtual machine hostedby a hypervisor executing on a computing device comprising one or moreprocessors and computer memory; and wherein the master monitor nodenotifies a storage manager that the second virtual machine has beenconfirmed failed; and wherein the storage manager manages storagemanagement operations in the data storage management system. Theabove-recited computer-readable medium further comprising: managing, bythe storage manager, a failover operation for the second virtualmachine, wherein a fourth virtual machine is activated to operate inplace of the failed second virtual machine. The above-recitedcomputer-readable medium further comprising: managing, by the storagemanager, a failover operation for the second virtual machine, wherein afourth virtual machine is activated to operate in place of the failedsecond virtual machine; and wherein prior to the failover operation, thestorage manager managed a replication operation of the second virtualmachine to the fourth virtual machine. The above-recitedcomputer-readable medium further comprising: managing, by the storagemanager, a failover operation for the second virtual machine, wherein afourth virtual machine is activated to operate in place of the failedsecond virtual machine; and wherein prior to the failover operation, thestorage manager managed a live synchronization operation of the secondvirtual machine to the fourth virtual machine. The above-recitedcomputer-readable medium wherein the first data agent is furtherconfigured to operate as a master monitor node; and wherein the mastermonitor node notifies a storage manager that the second virtual machinehas been confirmed failed, and wherein the storage manager managesstorage management operations in the data storage management system. Theabove-recited computer-readable medium wherein the first worker monitornode transmits a first respective data packet to each of the pluralityof virtual machines which are assigned to the first worker monitor nodefor heartbeat monitoring before transmitting a second respective datapacket to each of the plurality of virtual machines. The above-recitedcomputer-readable medium further comprising: for a given data packetfrom among the plurality of data packets transmitted to the secondvirtual machine, waiting by the first worker monitor node for aresponsive data packet to arrive within a predefined timeout interval;if the responsive data packet does not arrive within the predefinedtimeout interval, re-transmitting, by the first worker monitor node, thegiven data packet to the second virtual machine, wherein there-transmitting is limited to a predefined count. The above-recitedcomputer-readable medium wherein the rate of responses to the pluralityof data packets includes the re-transmitting of the given data packet.The above-recited computer-readable medium wherein the first workermonitor node executes an instance of Apache ZooKeeper server and clientservices and is part of a quorum that also includes the master monitornode. The above-recited computer-readable medium wherein the firstworker monitor node executes an instance of Apache ZooKeeper clientservices; wherein the master monitor node is part of a quorum of monitornodes; and wherein the first worker monitor node is not part of thequorum.

Yet one more illustrative embodiment comprises: a system for heartbeatmonitoring virtual machines in a data storage management systemcomprising: a first data agent configured to operate as a first workermonitor node, wherein the first data agent executes on one of: (i) acomputing device comprising one or more processors and computer memory,and (ii) a first virtual machine hosted by a hypervisor executing on acomputing device comprising one or more processors and computer memory;and wherein the first worker monitor node is configured to: transmit aplurality of data packets to a second virtual machine hosted by a firsthypervisor executing on a computing device comprising one or moreprocessors and computer memory, wherein the second virtual machine isone of a plurality of virtual machines which are assigned to the firstworker monitor node for heartbeat monitoring, when the first workermonitor node determines that a rate of responses to the plurality ofdata packets falls below a predefined threshold, querying one of: (a)the first hypervisor, and (b) a controller of a virtual machine datacenter comprising the first hypervisor about an operational status ofthe second virtual machine, and if, responsive to the querying, theoperational status of the second virtual machine is reported to befailed, (a) refraining from further transmitting of data packets by thefirst worker monitor node to the second virtual machine.

The above-recited system wherein if, responsive to the querying, theoperational status of the second virtual machine is reported to befailed, (b) reporting to a master monitor node that the second virtualmachine has been confirmed failed, wherein the reporting comprisesupdating, by the first worker monitor node, a data structure in adistributed file system having an instance on the first worker monitornode and on the master monitor node. The above-recited system furthercomprising: if, responsive to the querying, the operational status ofthe second virtual machine is reported to be active, resuming thetransmitting of data packets by the first worker monitor node to thesecond virtual machine. The above-recited system further comprising: if,responsive to the querying, the operational status of the second virtualmachine is reported to be undergoing maintenance, (i) suspending for atime period the transmitting of data packets by the first worker monitornode to the second virtual machine, and (ii) after the time periodexpires, querying again about the operational status of the secondvirtual machine. The above-recited system wherein a second data agent isconfigured to operate as a master monitor node and executes on one of(i) a computing device comprising one or more processors and computermemory, and (ii) a third virtual machine hosted by a hypervisorexecuting on a computing device comprising one or more processors andcomputer memory; and wherein the master monitor node notifies a storagemanager that the second virtual machine has been confirmed failed; andwherein the storage manager manages storage management operations in thedata storage management system. The above-recited system furthercomprising: managing, by the storage manager, a failover operation forthe second virtual machine, wherein a fourth virtual machine isactivated to operate in place of the failed second virtual machine. Theabove-recited system further comprising: managing, by the storagemanager, a failover operation for the second virtual machine, wherein afourth virtual machine is activated to operate in place of the failedsecond virtual machine; and wherein prior to the failover operation, thestorage manager managed a replication operation of the second virtualmachine to the fourth virtual machine. The above-recited system furthercomprising: managing, by the storage manager, a failover operation forthe second virtual machine, wherein a fourth virtual machine isactivated to operate in place of the failed second virtual machine; andwherein prior to the failover operation, the storage manager managed alive synchronization operation of the second virtual machine to thefourth virtual machine. The above-recited system wherein the first dataagent is further configured to operate as a master monitor node; andwherein the master monitor node notifies a storage manager that thesecond virtual machine has been confirmed failed, and wherein thestorage manager manages storage management operations in the datastorage management system. The above-recited system wherein the firstworker monitor node transmits a first respective data packet to each ofthe plurality of virtual machines which are assigned to the first workermonitor node for heartbeat monitoring before transmitting a secondrespective data packet to each of the plurality of virtual machines. Theabove-recited system further comprising: for a given data packet fromamong the plurality of data packets transmitted to the second virtualmachine, waiting by the first worker monitor node for a responsive datapacket to arrive within a predefined timeout interval; if the responsivedata packet does not arrive within the predefined timeout interval,re-transmitting, by the first worker monitor node, the given data packetto the second virtual machine, wherein the re-transmitting is limited toa predefined count. The above-recited system wherein the rate ofresponses to the plurality of data packets includes the re-transmittingof the given data packet. The above-recited system wherein the firstworker monitor node executes an instance of Apache ZooKeeper server andclient services and is part of a quorum that also includes the mastermonitor node. The above-recited system wherein the first worker monitornode executes an instance of Apache ZooKeeper client services; whereinthe master monitor node is part of a quorum of monitor nodes; andwherein the first worker monitor node is not part of the quorum.

According to another example embodiment, a method for heartbeatmonitoring virtual machines in a data storage management system, themethod comprising: heartbeat monitoring, by a first data agentconfigured to operate as a first worker monitor node, a second virtualmachine in the data storage management system, wherein the first dataagent executes on one of: (i) a computing device comprising one or moreprocessors and computer memory, and (ii) a first virtual machine hostedby a hypervisor executing on a computing device comprising one or moreprocessors and computer memory; and wherein the heartbeat monitoringcomprises: transmitting, from the first worker monitor node, a pluralityof data packets to a second virtual machine hosted by a first hypervisorexecuting on a computing device comprising one or more processors andcomputer memory, when the first worker monitor node determines that aloss rate of responses to the plurality of data packets exceeds apredefined threshold, querying one of: (a) the first hypervisor thathosts the second virtual machine, and (b) a controller of a virtualmachine data center comprising the first hypervisor, about anoperational status of the second virtual machine, and if, responsive tothe querying, the operational status of the second virtual machine isreported to be failed, (a) refraining by the first worker monitor nodefrom further transmitting data packets to the second virtual machine,and (b) updating by the first worker monitor node, with an indicationthat the second virtual machine is confirmed failed, a data structure ina distributed file system having an instance on the first worker monitornode.

The above-recited method wherein the heartbeat monitoring furthercomprises: if, responsive to the querying, the operational status of thesecond virtual machine is reported to be active, continuing thetransmitting of data packets by the first worker monitor node to thesecond virtual machine. The above-recited method wherein the heartbeatmonitoring further comprises: if, responsive to the querying, theoperational status of the second virtual machine is reported to beundergoing maintenance, (i) suspending for a time period thetransmitting of data packets by the first worker monitor node to thesecond virtual machine, and (ii) after the time period expires, queryingagain about the operational status of the second virtual machine. Theabove-recited method wherein the heartbeat monitoring further comprises:receiving, by a master monitor node in the data storage managementsystem, the indication that the second virtual machine is confirmedfailed, based on the master monitor node detecting the updating in aninstance of the distributed file system on the master monitor node; andnotifying a storage manager, by the master monitor node, that the secondvirtual machine is confirmed failed; and based on the notifying,managing by the storage manager, a failover operation of the secondvirtual machine to a third virtual machine that is configured toreplicate at least some operational characteristics of the secondvirtual machine, wherein the storage manager manages storage managementoperations in the data storage management system.

According to yet another example embodiment a computer-readable medium,excluding transitory propagating signals, storing instructions that,when executed by a computing device, cause the computing device toperform operations comprising: heartbeat monitoring, by a first dataagent configured to operate as a first worker monitor node, a secondvirtual machine in the data storage management system, wherein the firstdata agent executes on the computing device, which comprises one of: (i)one or more processors and computer memory, and (ii) a first virtualmachine hosted by a hypervisor executing on the computing device havingone or more processors and computer memory; and wherein the heartbeatmonitoring comprises: transmitting, from the first worker monitor node,a plurality of data packets to a second virtual machine hosted by afirst hypervisor executing on a computing device comprising one or moreprocessors and computer memory, when the first worker monitor nodedetermines that a loss rate of responses to the plurality of datapackets exceeds a predefined threshold, querying one of: (a) the firsthypervisor that hosts the second virtual machine, and (b) a controllerof a virtual machine data center comprising the first hypervisor, aboutan operational status of the second virtual machine, and if, responsiveto the querying, the operational status of the second virtual machine isreported to be failed, (a) refraining by the first worker monitor nodefrom further transmitting data packets to the second virtual machine,and (b) updating by the first worker monitor node, with an indicationthat the second virtual machine is confirmed failed, a data structure ina distributed file system having an instance on the first worker monitornode.

The above-recited computer-readable medium wherein the heartbeatmonitoring further comprises: if, responsive to the querying, theoperational status of the second virtual machine is reported to beactive, continuing the transmitting of data packets by the first workermonitor node to the second virtual machine. The above-recitedcomputer-readable medium wherein the heartbeat monitoring furthercomprises: if, responsive to the querying, the operational status of thesecond virtual machine is reported to be undergoing maintenance, (i)suspending for a time period the transmitting of data packets by thefirst worker monitor node to the second virtual machine, and (ii) afterthe time period expires, querying again about the operational status ofthe second virtual machine. The above-recited computer-readable mediumwherein the heartbeat monitoring further comprises: receiving, by amaster monitor node in the data storage management system, theindication that the second virtual machine is confirmed failed, based onthe master monitor node detecting the updating in an instance of thedistributed file system on the master monitor node; and notifying astorage manager, by the master monitor node, that the second virtualmachine is confirmed failed; and based on the notifying, managing by thestorage manager, a failover operation of the second virtual machine to athird virtual machine that is configured to replicate at least someoperational characteristics of the second virtual machine, wherein thestorage manager manages storage management operations in the datastorage management system.

According to one more example embodiment a system for heartbeatmonitoring virtual machines comprising: a first data agent configured tooperate as a first worker monitor node, wherein the first data agentexecutes on one of: (i) a computing device comprising one or moreprocessors and computer memory, and (ii) a first virtual machine hostedby a hypervisor executing on a computing device comprising one or moreprocessors and computer memory; and wherein the first worker monitornode is configured to: transmit a plurality of data packets to a secondvirtual machine hosted by a first hypervisor executing on a computingdevice comprising one or more processors and computer memory, when thefirst worker monitor node determines that a loss rate of responses tothe plurality of data packets exceeds a predefined threshold, queryingone of: (a) the first hypervisor that hosts the second virtual machine,and (b) a controller of a virtual machine data center comprising thefirst hypervisor, about an operational status of the second virtualmachine, and if, responsive to the querying, the operational status ofthe second virtual machine is reported to be failed, (a) refraining bythe first worker monitor node from further transmitting data packets tothe second virtual machine, and (b) updating by the first worker monitornode, with an indication that the second virtual machine is confirmedfailed, a data structure in a distributed file system having an instanceon the first worker monitor node.

The above-recited system wherein the heartbeat monitoring furthercomprises: if, responsive to the querying, the operational status of thesecond virtual machine is reported to be active, continuing thetransmitting of data packets by the first worker monitor node to thesecond virtual machine. The above-recited system wherein the heartbeatmonitoring further comprises: if, responsive to the querying, theoperational status of the second virtual machine is reported to beundergoing maintenance, (i) suspending for a time period thetransmitting of data packets by the first worker monitor node to thesecond virtual machine, and (ii) after the time period expires, queryingagain about the operational status of the second virtual machine. Theabove-recited system wherein the heartbeat monitoring further comprises:receiving, by a master monitor node in the data storage managementsystem, the indication that the second virtual machine is confirmedfailed, based on the master monitor node detecting the updating in aninstance of the distributed file system on the master monitor node; andnotifying a storage manager, by the master monitor node, that the secondvirtual machine is confirmed failed; and based on the notifying,managing by the storage manager, a failover operation of the secondvirtual machine to a third virtual machine that is configured toreplicate at least some operational characteristics of the secondvirtual machine, wherein the storage manager manages storage managementoperations in the data storage management system.

According to another example embodiment a method for assigning virtualmachines as targets for heartbeat monitoring by heartbeat monitor nodesin a data storage management system, the method comprising: validating,by a heartbeat monitor node, which is designated a master monitor node,whether a first set of virtual machines are operational in the datastorage management system, wherein the master monitor node comprises adata agent in communication with a storage manager, wherein the dataagent executes on one of (i) a nonvirtualized computing devicecomprising one or more processors and computer memory, and (ii) a firstvirtual machine executing on a computing device comprising one or moreprocessors and computer memory and executing a hypervisor, and whereinthe storage manager executes on a computing device comprising one ormore processors and computer memory, and wherein the storage managermanages storage management operations in the data storage managementsystem; wherein the validating comprises: obtaining from the storagemanager a first list of the first set of virtual machines that aretargeted for heartbeat monitoring by one or more heartbeat monitornodes, and querying one or more hypervisors operating in the datastorage management system to confirm whether the targeted first set ofvirtual machines are currently operational, resulting in a list ofconfirmed target virtual machines; based on distribution rules,assigning each target virtual machine on the list of confirmed targetvirtual machines to one of a plurality of worker monitor nodes,resulting in a worker-to-virtual-machine mapping; and performing, byeach of the plurality of worker monitor nodes, heartbeat monitoring ofone or more target virtual machines assigned thereto in the assigningoperation.

The above-recited method wherein before the assigning operation, each ofthe plurality of worker monitor nodes has been confirmed by the mastermonitor node to be operational in the data storage management system.The above-recited method further comprising: obtaining from the storagemanager a list of a second set of heartbeat monitor nodes that aredesignated worker monitor nodes in the data storage management system;querying at least one of: (a) one or more hypervisors operating in thedata storage management system, and (b) one or more nonvirtualizedcomputing devices in the data storage management system, to confirmwhether the designated worker monitor nodes are currently operational,resulting in a list of confirmed worker monitor nodes, which comprisesthe plurality of worker monitor nodes. The above-recited method furthercomprising: obtaining from the storage manager a list of a second set ofheartbeat monitor nodes that are designated worker monitor nodes in thedata storage management system; querying at least one of: (a) one ormore hypervisors operating in the data storage management system, and(b) one or more nonvirtualized computing devices in the data storagemanagement system, to confirm whether the designated worker monitornodes are currently operational, resulting in a list of confirmed workermonitor nodes, which comprises the plurality of worker monitor nodes;and transmitting the worker-to-virtual-machine mapping to each of theconfirmed worker monitor nodes, thereby enabling each confirmed workermonitor node to perform the heartbeat monitoring of respective one ormore confirmed target virtual machines assigned thereto in the assigningoperation. The above-recited method wherein the master monitor node alsooperates as one of the plurality of worker monitor nodes.

The above-recited method wherein the distribution rules favor assigninga given target virtual machine on the list of confirmed target virtualmachines to a first worker monitor node that operates on the samevirtual machine network and is hosted by the same virtual machine hostserver as the given target virtual machine, as compared to assigning thegiven virtual machine to a second worker monitor node that operates onthe same virtual machine network as and is hosted by a different virtualmachine host server than the given target virtual machine. Theabove-recited method wherein the distribution rules favor assigning agiven target virtual machine on the list of confirmed target virtualmachines to a second worker monitor node that operates on the samevirtual machine network as and is hosted by a different virtual machinehost server than the given target virtual machine, as compared toassigning the given virtual machine to a third worker monitor node thatoperates on a different virtual machine network than and is hosted bythe same virtual machine host server as the given target virtualmachine. The above-recited method wherein the distribution rules favorassigning a given target virtual machine on the list of confirmed targetvirtual machines to a third worker monitor node that operates on adifferent virtual machine network than and is hosted by the same virtualmachine host server as the given target virtual machine, as compared toassigning the given target virtual machine to a fourth worker monitornode having an acceptable hop count from the given target virtualmachine. The above-recited method wherein the distribution rules favorassigning a given target virtual machine on the list of confirmed targetvirtual machines to a fourth worker monitor node having an acceptablehop count from the given target virtual machine, as compared toassigning the given target virtual machine to a fifth worker monitornode that operates on the same subnetwork as the given target virtualmachine. The above-recited method wherein the distribution rules favorassigning a given target virtual machine on the list of confirmed targetvirtual machines to a fifth worker monitor node that operates on thesame subnetwork as the given target virtual machine, as compared toassigning the given target virtual machine to a sixth worker monitornode having an acceptable ping-latency from the given target virtualmachine. The above-recited method wherein the distribution rulescomprise an order of preferences for assigning a given target virtualmachine on the list of confirmed target virtual machines to a workermonitor node; wherein the order of preferences favor assigning the giventarget virtual machine to a first worker monitor node that operates onthe same virtual machine network and is hosted by the same virtualmachine host server as the given target virtual machine, as compared toassigning the given virtual machine to a second worker monitor node thatoperates on the same virtual machine network as and is hosted by adifferent virtual machine host server than the given target virtualmachine; wherein the order of preferences favor assigning the giventarget virtual machine to the second worker monitor node that operateson the same virtual machine network as and is hosted by a differentvirtual machine host server than the given target virtual machine, ascompared to assigning the given virtual machine to a third workermonitor node that operates on a different virtual machine network thanand is hosted by the same virtual machine host server as the giventarget virtual machine; wherein the order of preferences favor assigningthe given target virtual machine to the third worker monitor node thatoperates on a different virtual machine network than and is hosted bythe same virtual machine host server as the given target virtualmachine, as compared to assigning the given target virtual machine to afourth worker monitor node having an acceptable hop count from the giventarget virtual machine; wherein the order of preferences favor assigningthe given target virtual machine to the fourth worker monitor nodehaving an acceptable hop count from the given target virtual machine, ascompared to assigning the given target virtual machine to a fifth workermonitor node that operates on the same subnetwork as the given targetvirtual machine; and wherein the order of preferences favor assigningthe given target virtual machine to the fifth worker monitor node thatoperates on the same subnetwork as the given target virtual machine, ascompared to assigning the given target virtual machine to a sixth workermonitor node having an acceptable ping-latency from the given targetvirtual machine. The above-recited method wherein theworker-to-virtual-machine mapping is transmitted to each of theplurality of worker monitor nodes by a distributed file system having aninstance on each of the plurality of worker monitor nodes. Theabove-recited method wherein the worker-to-virtual-machine mapping istransmitted to each of the plurality of worker monitor nodes by adistributed file system having an instance on each of the plurality ofworker monitor nodes, wherein the distributed file system is based onApache ZooKeeper services. The above-recited method wherein the mastermonitor node executes an instance of Apache ZooKeeper server and clientservices. The above-recited method wherein the master monitor node andat least one of the plurality of worker monitor nodes is part of aquorum based on Apache ZooKeeper services. The above-recited methodwherein the master monitor node executes an instance of Apache ZooKeeperserver and client services; and wherein the master monitor node and atleast one of the plurality of worker monitor nodes is part of a quorumbased on Apache ZooKeeper services.

According to yet another example embodiment a computer-readable medium,excluding transitory propagating signals, storing instructions that,when executed by a computing device, cause the computing device toperform operations comprising: validating, by a heartbeat monitor node,which is designated a master monitor node, whether a first set ofvirtual machines are operational in the data storage management system,wherein the master monitor node comprises a data agent in communicationwith a storage manager, wherein the data agent executes on the computingdevice comprising one of: (i) one or more processors and computermemory, and (ii) a first virtual machine hosted by a hypervisorexecuting on one or more processors and computer memory, and wherein thestorage manager executes on a computing device comprising one or moreprocessors and computer memory, and wherein the storage manager managesstorage management operations in the data storage management system;wherein the validating comprises: obtaining from the storage manager afirst list of the first set of virtual machines that are targeted forheartbeat monitoring by one or more heartbeat monitor nodes, andquerying one or more hypervisors operating in the data storagemanagement system to confirm whether the targeted first set of virtualmachines are currently operational, resulting in a list of confirmedtarget virtual machines; based on distribution rules, assigning eachtarget virtual machine on the list of confirmed target virtual machinesto one of a plurality of worker monitor nodes, resulting in aworker-to-virtual-machine mapping; and performing, by each of theplurality of worker monitor nodes, heartbeat monitoring of one or moretarget virtual machines assigned thereto in the assigning operation.

The above-recited computer-readable medium wherein before the assigningoperation, each of the plurality of worker monitor nodes has beenconfirmed by the master monitor node to be operational in the datastorage management system. The above-recited computer-readable mediumfurther comprising: obtaining from the storage manager a list of asecond set of heartbeat monitor nodes that are designated worker monitornodes in the data storage management system; querying at least one of:(a) one or more hypervisors operating in the data storage managementsystem, and (b) one or more nonvirtualized computing devices in the datastorage management system, to confirm whether the designated workermonitor nodes are currently operational, resulting in a list ofconfirmed worker monitor nodes, which comprises the plurality of workermonitor nodes. The above-recited computer-readable medium furthercomprising: obtaining from the storage manager a list of a second set ofheartbeat monitor nodes that are designated worker monitor nodes in thedata storage management system; querying at least one of: (a) one ormore hypervisors operating in the data storage management system, and(b) one or more nonvirtualized computing devices in the data storagemanagement system, to confirm whether the designated worker monitornodes are currently operational, resulting in a list of confirmed workermonitor nodes, which comprises the plurality of worker monitor nodes;and transmitting the worker-to-virtual-machine mapping to each of theconfirmed worker monitor nodes, thereby enabling each confirmed workermonitor node to perform the heartbeat monitoring of respective one ormore confirmed target virtual machines assigned thereto in the assigningoperation. The above-recited computer-readable medium wherein the mastermonitor node also operates as one of the plurality of worker monitornodes.

The above-recited computer-readable medium wherein the distributionrules favor assigning a given target virtual machine on the list ofconfirmed target virtual machines to a first worker monitor node thatoperates on the same virtual machine network and is hosted by the samevirtual machine host server as the given target virtual machine, ascompared to assigning the given virtual machine to a second workermonitor node that operates on the same virtual machine network as and ishosted by a different virtual machine host server than the given targetvirtual machine. The above-recited computer-readable medium wherein thedistribution rules favor assigning a given target virtual machine on thelist of confirmed target virtual machines to a second worker monitornode that operates on the same virtual machine network as and is hostedby a different virtual machine host server than the given target virtualmachine, as compared to assigning the given virtual machine to a thirdworker monitor node that operates on a different virtual machine networkthan and is hosted by the same virtual machine host server as the giventarget virtual machine. The above-recited computer-readable mediumwherein the distribution rules favor assigning a given target virtualmachine on the list of confirmed target virtual machines to a thirdworker monitor node that operates on a different virtual machine networkthan and is hosted by the same virtual machine host server as the giventarget virtual machine, as compared to assigning the given targetvirtual machine to a fourth worker monitor node having an acceptable hopcount from the given target virtual machine. The above-recitedcomputer-readable medium wherein the distribution rules favor assigninga given target virtual machine on the list of confirmed target virtualmachines to a fourth worker monitor node having an acceptable hop countfrom the given target virtual machine, as compared to assigning thegiven target virtual machine to a fifth worker monitor node thatoperates on the same subnetwork as the given target virtual machine. Theabove-recited computer-readable medium wherein the distribution rulesfavor assigning a given target virtual machine on the list of confirmedtarget virtual machines to a fifth worker monitor node that operates onthe same subnetwork as the given target virtual machine, as compared toassigning the given target virtual machine to a sixth worker monitornode having an acceptable ping-latency from the given target virtualmachine. The above-recited computer-readable medium wherein thedistribution rules comprise an order of preferences for assigning agiven target virtual machine on the list of confirmed target virtualmachines to a worker monitor node; wherein the order of preferencesfavor assigning the given target virtual machine to a first workermonitor node that operates on the same virtual machine network and ishosted by the same virtual machine host server as the given targetvirtual machine, as compared to assigning the given virtual machine to asecond worker monitor node that operates on the same virtual machinenetwork as and is hosted by a different virtual machine host server thanthe given target virtual machine; wherein the order of preferences favorassigning the given target virtual machine to the second worker monitornode that operates on the same virtual machine network as and is hostedby a different virtual machine host server than the given target virtualmachine, as compared to assigning the given virtual machine to a thirdworker monitor node that operates on a different virtual machine networkthan and is hosted by the same virtual machine host server as the giventarget virtual machine; wherein the order of preferences favor assigningthe given target virtual machine to the third worker monitor node thatoperates on a different virtual machine network than and is hosted bythe same virtual machine host server as the given target virtualmachine, as compared to assigning the given target virtual machine to afourth worker monitor node having an acceptable hop count from the giventarget virtual machine; wherein the order of preferences favor assigningthe given target virtual machine to the fourth worker monitor nodehaving an acceptable hop count from the given target virtual machine, ascompared to assigning the given target virtual machine to a fifth workermonitor node that operates on the same subnetwork as the given targetvirtual machine; and wherein the order of preferences favor assigningthe given target virtual machine to the fifth worker monitor node thatoperates on the same subnetwork as the given target virtual machine, ascompared to assigning the given target virtual machine to a sixth workermonitor node having an acceptable ping-latency from the given targetvirtual machine. The above-recited computer-readable medium wherein theworker-to-virtual-machine mapping is transmitted to each of theplurality of worker monitor nodes by a distributed file system having aninstance on each of the plurality of worker monitor nodes. Theabove-recited computer-readable medium wherein theworker-to-virtual-machine mapping is transmitted to each of theplurality of worker monitor nodes by a distributed file system having aninstance on each of the plurality of worker monitor nodes, wherein thedistributed file system is based on Apache ZooKeeper services. Theabove-recited computer-readable medium wherein the master monitor nodeexecutes an instance of Apache ZooKeeper server and client services. Theabove-recited computer-readable medium wherein the master monitor nodeand at least one of the plurality of worker monitor nodes is part of aquorum based on Apache ZooKeeper services. The above-recitedcomputer-readable medium wherein the master monitor node executes aninstance of Apache ZooKeeper server and client services; and wherein themaster monitor node and at least one of the plurality of worker monitornodes is part of a quorum based on Apache ZooKeeper services.

According to yet one more example embodiment a system for assigningvirtual machines as targets for heartbeat monitoring by heartbeatmonitor nodes in a data storage management system, the systemcomprising: a data agent that executes on the computing devicecomprising one of: (i) one or more processors and computer memory, and(ii) a first virtual machine hosted by a hypervisor executing on one ormore processors and computer memory; wherein the data agent isconfigured to operate as a master monitor node for validating whether afirst set of virtual machines are operational in the data storagemanagement system, wherein the master monitor node is in communicationwith a storage manager that executes on a computing device comprisingone or more processors and computer memory, and wherein the storagemanager manages storage management operations in the data storagemanagement system; wherein the validating by the master monitor nodecomprises: obtaining from the storage manager a first list of the firstset of virtual machines that are targeted for heartbeat monitoring byone or more heartbeat monitor nodes, and querying one or morehypervisors operating in the data storage management system to confirmwhether the targeted first set of virtual machines are currentlyoperational, resulting in a list of confirmed target virtual machines;based on distribution rules, assigning each target virtual machine onthe list of confirmed target virtual machines to one of a plurality ofworker monitor nodes, resulting in a worker-to-virtual-machine mapping;and performing, by each of the plurality of worker monitor nodes,heartbeat monitoring of one or more target virtual machines assignedthereto in the assigning operation.

The above-recited system wherein before the assigning operation, each ofthe plurality of worker monitor nodes has been confirmed by the mastermonitor node to be operational in the data storage management system.The above-recited system further comprising: obtaining from the storagemanager a list of a second set of heartbeat monitor nodes that aredesignated worker monitor nodes in the data storage management system;querying at least one of: (a) one or more hypervisors operating in thedata storage management system, and (b) one or more nonvirtualizedcomputing devices in the data storage management system, to confirmwhether the designated worker monitor nodes are currently operational,resulting in a list of confirmed worker monitor nodes, which comprisesthe plurality of worker monitor nodes. The above-recited system furthercomprising: obtaining from the storage manager a list of a second set ofheartbeat monitor nodes that are designated worker monitor nodes in thedata storage management system; querying at least one of: (a) one ormore hypervisors operating in the data storage management system, and(b) one or more nonvirtualized computing devices in the data storagemanagement system, to confirm whether the designated worker monitornodes are currently operational, resulting in a list of confirmed workermonitor nodes, which comprises the plurality of worker monitor nodes;and transmitting the worker-to-virtual-machine mapping to each of theconfirmed worker monitor nodes, thereby enabling each confirmed workermonitor node to perform the heartbeat monitoring of respective one ormore confirmed target virtual machines assigned thereto in the assigningoperation. The above-recited system wherein the master monitor node alsooperates as one of the plurality of worker monitor nodes.

The above-recited system wherein the distribution rules favor assigninga given target virtual machine on the list of confirmed target virtualmachines to a first worker monitor node that operates on the samevirtual machine network and is hosted by the same virtual machine hostserver as the given target virtual machine, as compared to assigning thegiven virtual machine to a second worker monitor node that operates onthe same virtual machine network as and is hosted by a different virtualmachine host server than the given target virtual machine. Theabove-recited system wherein the distribution rules favor assigning agiven target virtual machine on the list of confirmed target virtualmachines to a second worker monitor node that operates on the samevirtual machine network as and is hosted by a different virtual machinehost server than the given target virtual machine, as compared toassigning the given virtual machine to a third worker monitor node thatoperates on a different virtual machine network than and is hosted bythe same virtual machine host server as the given target virtualmachine. The above-recited system wherein the distribution rules favorassigning a given target virtual machine on the list of confirmed targetvirtual machines to a third worker monitor node that operates on adifferent virtual machine network than and is hosted by the same virtualmachine host server as the given target virtual machine, as compared toassigning the given target virtual machine to a fourth worker monitornode having an acceptable hop count from the given target virtualmachine. The above-recited system wherein the distribution rules favorassigning a given target virtual machine on the list of confirmed targetvirtual machines to a fourth worker monitor node having an acceptablehop count from the given target virtual machine, as compared toassigning the given target virtual machine to a fifth worker monitornode that operates on the same subnetwork as the given target virtualmachine. The above-recited system wherein the distribution rules favorassigning a given target virtual machine on the list of confirmed targetvirtual machines to a fifth worker monitor node that operates on thesame subnetwork as the given target virtual machine, as compared toassigning the given target virtual machine to a sixth worker monitornode having an acceptable ping-latency from the given target virtualmachine. The above-recited system wherein the distribution rulescomprise an order of preferences for assigning a given target virtualmachine on the list of confirmed target virtual machines to a workermonitor node; wherein the order of preferences favor assigning the giventarget virtual machine to a first worker monitor node that operates onthe same virtual machine network and is hosted by the same virtualmachine host server as the given target virtual machine, as compared toassigning the given virtual machine to a second worker monitor node thatoperates on the same virtual machine network as and is hosted by adifferent virtual machine host server than the given target virtualmachine; wherein the order of preferences favor assigning the giventarget virtual machine to the second worker monitor node that operateson the same virtual machine network as and is hosted by a differentvirtual machine host server than the given target virtual machine, ascompared to assigning the given virtual machine to a third workermonitor node that operates on a different virtual machine network thanand is hosted by the same virtual machine host server as the giventarget virtual machine; wherein the order of preferences favor assigningthe given target virtual machine to the third worker monitor node thatoperates on a different virtual machine network than and is hosted bythe same virtual machine host server as the given target virtualmachine, as compared to assigning the given target virtual machine to afourth worker monitor node having an acceptable hop count from the giventarget virtual machine; wherein the order of preferences favor assigningthe given target virtual machine to the fourth worker monitor nodehaving an acceptable hop count from the given target virtual machine, ascompared to assigning the given target virtual machine to a fifth workermonitor node that operates on the same subnetwork as the given targetvirtual machine; and wherein the order of preferences favor assigningthe given target virtual machine to the fifth worker monitor node thatoperates on the same subnetwork as the given target virtual machine, ascompared to assigning the given target virtual machine to a sixth workermonitor node having an acceptable ping-latency from the given targetvirtual machine. The above-recited system wherein theworker-to-virtual-machine mapping is transmitted to each of theplurality of worker monitor nodes by a distributed file system having aninstance on each of the plurality of worker monitor nodes. Theabove-recited system wherein the worker-to-virtual-machine mapping istransmitted to each of the plurality of worker monitor nodes by adistributed file system having an instance on each of the plurality ofworker monitor nodes, wherein the distributed file system is based onApache ZooKeeper services. The above-recited system wherein the mastermonitor node executes an instance of Apache ZooKeeper server and clientservices. The above-recited system wherein the master monitor node andat least one of the plurality of worker monitor nodes is part of aquorum based on Apache ZooKeeper services. The above-recited systemwherein the master monitor node executes an instance of Apache ZooKeeperserver and client services; and wherein the master monitor node and atleast one of the plurality of worker monitor nodes is part of a quorumbased on Apache ZooKeeper services.

Some example enumerated embodiments of the present invention are hereinin the form of methods, systems, and non-transitory computer-readablemedia, without limitation. In other embodiments, a system or systems mayoperate according to one or more of the methods and/or computer-readablemedia recited in the preceding paragraphs. In yet other embodiments, amethod or methods may operate according to one or more of the systemsand/or computer-readable media recited in the preceding paragraphs. Inyet more embodiments, a computer-readable medium or media, excludingtransitory propagating signals, may cause one or more computing deviceshaving one or more processors and non-transitory computer-readablememory to operate according to one or more of the systems and/or methodsrecited in the preceding paragraphs.

Terminology

Conditional language, such as, among others, “can,” “could,” “might,” or“may,” unless specifically stated otherwise, or otherwise understoodwithin the context as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements and/or steps. Thus, such conditional language is notgenerally intended to imply that features, elements and/or steps are inany way required for one or more embodiments or that one or moreembodiments necessarily include logic for deciding, with or without userinput or prompting, whether these features, elements and/or steps areincluded or are to be performed in any particular embodiment.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense, i.e., in the sense of “including, but notlimited to.” As used herein, the terms “connected,” “coupled,” or anyvariant thereof means any connection or coupling, either direct orindirect, between two or more elements; the coupling or connectionbetween the elements can be physical, logical, or a combination thereof.Additionally, the words “herein,” “above,” “below,” and words of similarimport, when used in this application, refer to this application as awhole and not to any particular portions of this application. Where thecontext permits, words using the singular or plural number may alsoinclude the plural or singular number respectively. The word “or” inreference to a list of two or more items, covers all of the followinginterpretations of the word: any one of the items in the list, all ofthe items in the list, and any combination of the items in the list.Likewise the term “and/or” in reference to a list of two or more items,covers all of the following interpretations of the word: any one of theitems in the list, all of the items in the list, and any combination ofthe items in the list.

In some embodiments, certain operations, acts, events, or functions ofany of the algorithms described herein can be performed in a differentsequence, can be added, merged, or left out altogether (e.g., not allare necessary for the practice of the algorithms). In certainembodiments, operations, acts, functions, or events can be performedconcurrently, e.g., through multi-threaded processing, interruptprocessing, or multiple processors or processor cores or on otherparallel architectures, rather than sequentially.

Systems and modules described herein may comprise software, firmware,hardware, or any combination(s) of software, firmware, or hardwaresuitable for the purposes described. Software and other modules mayreside and execute on servers, workstations, personal computers,computerized tablets, PDAs, and other computing devices suitable for thepurposes described herein. Software and other modules may be accessiblevia local computer memory, via a network, via a browser, or via othermeans suitable for the purposes described herein. Data structuresdescribed herein may comprise computer files, variables, programmingarrays, programming structures, or any electronic information storageschemes or methods, or any combinations thereof, suitable for thepurposes described herein. User interface elements described herein maycomprise elements from graphical user interfaces, interactive voiceresponse, command line interfaces, and other suitable interfaces.

Further, processing of the various components of the illustrated systemscan be distributed across multiple machines, networks, and othercomputing resources. Two or more components of a system can be combinedinto fewer components. Various components of the illustrated systems canbe implemented in one or more virtual machines, rather than in dedicatedcomputer hardware systems and/or computing devices. Likewise, the datarepositories shown can represent physical and/or logical data storage,including, e.g., storage area networks or other distributed storagesystems. Moreover, in some embodiments the connections between thecomponents shown represent possible paths of data flow, rather thanactual connections between hardware. While some examples of possibleconnections are shown, any of the subset of the components shown cancommunicate with any other subset of components in variousimplementations.

Embodiments are also described above with reference to flow chartillustrations and/or block diagrams of methods, apparatus (systems) andcomputer program products. Each block of the flow chart illustrationsand/or block diagrams, and combinations of blocks in the flow chartillustrations and/or block diagrams, may be implemented by computerprogram instructions. Such instructions may be provided to a processorof a general purpose computer, special purpose computer,specially-equipped computer (e.g., comprising a high-performancedatabase server, a graphics subsystem, etc.) or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which execute via the processor(s) of the computer or other programmabledata processing apparatus, create means for implementing the actsspecified in the flow chart and/or block diagram block or blocks. Thesecomputer program instructions may also be stored in a non-transitorycomputer-readable memory that can direct a computer or otherprogrammable data processing apparatus to operate in a particularmanner, such that the instructions stored in the computer-readablememory produce an article of manufacture including instruction meanswhich implement the acts specified in the flow chart and/or blockdiagram block or blocks. The computer program instructions may also beloaded to a computing device or other programmable data processingapparatus to cause operations to be performed on the computing device orother programmable apparatus to produce a computer implemented processsuch that the instructions which execute on the computing device orother programmable apparatus provide steps for implementing the actsspecified in the flow chart and/or block diagram block or blocks.

Any patents and applications and other references noted above, includingany that may be listed in accompanying filing papers, are incorporatedherein by reference. Aspects of the invention can be modified, ifnecessary, to employ the systems, functions, and concepts of the variousreferences described above to provide yet further implementations of theinvention. These and other changes can be made to the invention in lightof the above Detailed Description. While the above description describescertain examples of the invention, and describes the best modecontemplated, no matter how detailed the above appears in text, theinvention can be practiced in many ways. Details of the system may varyconsiderably in its specific implementation, while still beingencompassed by the invention disclosed herein. As noted above,particular terminology used when describing certain features or aspectsof the invention should not be taken to imply that the terminology isbeing redefined herein to be restricted to any specific characteristics,features, or aspects of the invention with which that terminology isassociated. In general, the terms used in the following claims shouldnot be construed to limit the invention to the specific examplesdisclosed in the specification, unless the above Detailed Descriptionsection explicitly defines such terms. Accordingly, the actual scope ofthe invention encompasses not only the disclosed examples, but also allequivalent ways of practicing or implementing the invention under theclaims.

To reduce the number of claims, certain aspects of the invention arepresented below in certain claim forms, but the applicant contemplatesother aspects of the invention in any number of claim forms. Forexample, while only one aspect of the invention is recited as ameans-plus-function claim under 35 U.S.C sec. 112(f) (AIA), otheraspects may likewise be embodied as a means-plus-function claim, or inother forms, such as being embodied in a computer-readable medium. Anyclaims intended to be treated under 35 U.S.C. § 112(f) will begin withthe words “means for,” but use of the term “for” in any other context isnot intended to invoke treatment under 35 U.S.C. § 112(f). Accordingly,the applicant reserves the right to pursue additional claims afterfiling this application, in either this application or in a continuingapplication.

What is claimed is:
 1. A method comprising: configuring a first dataagent as a master monitor node in a data storage management system formanaging worker monitor nodes, wherein: the master monitor nodecomprises a local copy of a first data file for managing the heartbeatmonitoring of the virtual machines, and changes to the first data fileare propagated to other monitor nodes in the data storage managementsystem; configuring a second data agent as a first worker monitor nodein the data storage management system, wherein: the first worker monitornode performs heartbeat monitoring of a plurality of virtual machinesassigned by the master monitor node, and the first worker monitor nodecomprises a corresponding local copy of the first data file thatindicates the plurality of virtual machines to be monitored by the firstworker monitor node; detecting, by the master monitor node, that thefirst worker monitor node has failed based on a change to at least onefile of a distributed file system accessible by the master monitor nodeand the first worker monitor node; querying for the operational statusof the second data agent; and in response to the querying that thesecond data agent has failed: re-assigning, by the master monitor node,the plurality of virtual machines assigned to the failed first workermonitor node to a third data agent configured as a second worker monitornode in the data storage management system; and updating the first datafile to show the reassignment of the plurality of virtual machines,which is propagated by the distributed file system to other monitornodes in the storage management system.
 2. The method of claim 1,wherein: the first data agent executes on one of (i) a nonvirtualizedcomputing device comprising one or more processors and computer memory,and (ii) a first virtual machine hosted by a hypervisor executing on acomputing device comprising one or more processors and computer memory.3. The method of claim 1, wherein: the second data agent executes on oneof (i) a nonvirtualized computing device comprising one or moreprocessors and computer memory, and (ii) a second virtual machine hostedby a hypervisor executing on a computing device comprising one or moreprocessors and computer memory
 4. The method of claim 3, whereinquerying for the operational status of the second data agent comprises:querying one of: (a) the nonvirtualized computing device, (b) thehypervisor that hosts the second virtual machine, and (c) a controllerof a virtual machine data center comprising the second virtual machineabout the operational status of the second data agent.
 5. The method ofclaim 1, further comprising: monitoring, by the second worker monitornode, the plurality of virtual machines assigned thereto by the mastermonitor node.
 6. The method of claim 1, wherein the master monitor nodeassigns the plurality of virtual machines to the first monitor workernode based on a proximity of each of the plurality of virtual machinesto the first monitor worker node within a network topology.
 7. Themethod of claim 1, further comprising: initiating, by a storage managerof the data storage management system, a failover operation for a firstvirtual machine of the plurality of virtual machines, wherein thefailover operation activates a second virtual machine located in asecond region of a cloud service provider to operate in place of afailed first virtual machine of the plurality of virtual machineslocated in a first region of a cloud service provider.
 8. A systemcomprising: one or more non-transitory, computer-readable mediums havingcomputer-executable instructions stored thereon; and one or moreprocessors that, having executed the computer-executable instructions,configure the system to perform a plurality of operations comprising:configuring a first data agent as a master monitor node in a datastorage management system for managing worker monitor nodes, wherein:the master monitor node comprises a local copy of a first data file formanaging the heartbeat monitoring of the virtual machines, and changesto the first data file are propagated to other monitor nodes in the datastorage management system; configuring a second data agent as a firstworker monitor node in the data storage management system, wherein: thefirst worker monitor node performs heartbeat monitoring of a pluralityof virtual machines assigned by the master monitor node, and the firstworker monitor node comprises a corresponding local copy of the firstdata file that indicates the plurality of virtual machines to bemonitored by the first worker monitor node; detecting, by the mastermonitor node, that the first worker monitor node has failed based on achange to at least one file of a distributed file system accessible bythe master monitor node and the first worker monitor node; querying forthe operational status of the second data agent; and in response to thequerying that the second data agent has failed: re-assigning, by themaster monitor node, the plurality of virtual machines assigned to thefailed first worker monitor node to a third data agent configured as asecond worker monitor node in the data storage management system; andupdating the first data file to show the reassignment of the pluralityof virtual machines, which is propagated by the distributed file systemto other monitor nodes in the storage management system.
 9. The systemof claim 8, wherein: the first data agent executes on one of (i) anonvirtualized computing device comprising one or more processors andcomputer memory, and (ii) a first virtual machine hosted by a hypervisorexecuting on a computing device comprising one or more processors andcomputer memory.
 10. The system of claim 8, wherein: the second dataagent executes on one of (i) a nonvirtualized computing devicecomprising one or more processors and computer memory, and (ii) a secondvirtual machine hosted by a hypervisor executing on a computing devicecomprising one or more processors and computer memory
 11. The system ofclaim 10, wherein querying for the operational status of the second dataagent comprises: querying one of: (a) the nonvirtualized computingdevice, (b) the hypervisor that hosts the second virtual machine, and(c) a controller of a virtual machine data center comprising the secondvirtual machine about the operational status of the second data agent.12. The system of claim 8, wherein the plurality of operations furthercomprises: monitoring, by the second worker monitor node, the pluralityof virtual machines assigned thereto by the master monitor node.
 13. Thesystem of claim 8, wherein the master monitor node assigns the pluralityof virtual machines to the first monitor worker node based on aproximity of each of the plurality of virtual machines to the firstmonitor worker node within a network topology.
 14. The system of claim8, wherein the plurality of operations further comprises: initiating, bya storage manager of the data storage management system, a failoveroperation for a first virtual machine of the plurality of virtualmachines, wherein the failover operation activates a second virtualmachine located in a second region of a cloud service provider tooperate in place of a failed first virtual machine of the plurality ofvirtual machines located in a first region of a cloud service provider.15. A non-transitory, computer-readable medium havingcomputer-executable instructions stored thereon that, when executed byone or more processors, cause a system to perform a method comprising:configuring a first data agent as a master monitor node in a datastorage management system for managing worker monitor nodes, wherein:the master monitor node comprises a local copy of a first data file formanaging the heartbeat monitoring of the virtual machines, and changesto the first data file are propagated to other monitor nodes in the datastorage management system; configuring a second data agent as a firstworker monitor node in the data storage management system, wherein: thefirst worker monitor node performs heartbeat monitoring of a pluralityof virtual machines assigned by the master monitor node, and the firstworker monitor node comprises a corresponding local copy of the firstdata file that indicates the plurality of virtual machines to bemonitored by the first worker monitor node; detecting, by the mastermonitor node, that the first worker monitor node has failed based on achange to at least one file of a distributed file system accessible bythe master monitor node and the first worker monitor node; querying forthe operational status of the second data agent; and in response to thequerying that the second data agent has failed: re-assigning, by themaster monitor node, the plurality of virtual machines assigned to thefailed first worker monitor node to a third data agent configured as asecond worker monitor node in the data storage management system; andupdating the first data file to show the reassignment of the pluralityof virtual machines, which is propagated by the distributed file systemto other monitor nodes in the storage management system.
 16. Thenon-transitory, computer-readable medium of claim 15, wherein: the firstdata agent executes on one of (i) a nonvirtualized computing devicecomprising one or more processors and computer memory, and (ii) a firstvirtual machine hosted by a hypervisor executing on a computing devicecomprising one or more processors and computer memory.
 17. Thenon-transitory, computer-readable medium of claim 15, wherein: thesecond data agent executes on one of (i) a nonvirtualized computingdevice comprising one or more processors and computer memory, and (ii) asecond virtual machine hosted by a hypervisor executing on a computingdevice comprising one or more processors and computer memory
 18. Thenon-transitory, computer-readable medium of claim 17, wherein queryingfor the operational status of the second data agent comprises: queryingone of: (a) the nonvirtualized computing device, (b) the hypervisor thathosts the second virtual machine, and (c) a controller of a virtualmachine data center comprising the second virtual machine about theoperational status of the second data agent.
 19. The non-transitory,computer-readable medium of claim 15, wherein the method furthercomprises: monitoring, by the second worker monitor node, the pluralityof virtual machines assigned thereto by the master monitor node.
 20. Thenon-transitory, computer-readable medium of claim 15, wherein the mastermonitor node assigns the plurality of virtual machines to the firstmonitor worker node based on a proximity of each of the plurality ofvirtual machines to the first monitor worker node within a networktopology.